Spontaneous and stimulus-induced coherent states of critically balanced neuronal networks

How the information microscopically processed by individual neurons is integrated and used in organizing the behavior of an animal is a central question in neuroscience. The coherence of neuronal dynamics over different scales has been suggested as a clue to the mechanisms underlying this integration. Balanced excitation and inhibition may amplify microscopic fluctuations to a macroscopic level, thus providing a mechanism for generating coherent multiscale dynamics. Previous theories of brain dynamics, however, were restricted to cases in which inhibition dominated excitation and suppressed fluctuations in the macroscopic population activity. In the present study, we investigate the dynamics of neuronal networks at a critical point between excitation-dominant and inhibition-dominant states. In these networks, the microscopic fluctuations are amplified by the strong excitation and inhibition to drive the macroscopic dynamics, while the macroscopic dynamics determine the statistics of the microscopic fluctuations. Developing a novel type of mean-field theory applicable to this class of interscale interactions, we show that the amplification mechanism generates spontaneous, irregular macroscopic rhythms similar to those observed in the brain. Through the same mechanism, microscopic inputs to a small number of neurons effectively entrain the dynamics of the whole network. These network dynamics undergo a probabilistic transition to a coherent state, as the magnitude of either the balanced excitation and inhibition or the external inputs is increased. Our mean-field theory successfully predicts the behavior of this model. Furthermore, we numerically demonstrate that the coherent dynamics can be used for state-dependent read-out of information from the network. These results show a novel form of neuronal information processing that connects neuronal dynamics on different scales.Comment: 20 pages 12 figures (main text) + 23 pages 6 figures (Appendix); Some of the results have been removed in the revision in order to reduce the volume. See the previous version for more result

Controlled motion of Janus particles in periodically phase-separating binary fluids

We numerically investigate the propelled motions of a Janus particle in a periodically phase-separating binary fluid mixture. In this study, the surface of the particle tail prefers one of the binary fluid components and the particle head is neutral in the wettability. During the demixing period, the more wettable phase is selectively adsorbed to the particle tail. Growths of the adsorbed domains induce the hydrodynamic flow in the vicinity of the particle tail, and this asymmetric pumping flow drives the particle toward the particle head. During the mixing period, the particle motion almost ceases because the mixing primarily occurs via diffusion and the resulting hydrodynamic flow is negligibly small. Repeating this cycle unboundedly moves the Janus particle toward the head. The dependencies of the composition and the repeat frequency on the particle motion are discussed.Comment: 11 pages, 9 figure

Proof of completeness of the local conserved quantities in the one-dimensional Hubbard model

We rigorously prove that the local conserved quantities in the one-dimensional Hubbard model are uniquely determined for each locality up to the freedom to add lower-order ones. From this, we can conclude that the local conserved quantities are exhausted by those obtained from the expansion of the transfer matrix.Comment: Corrected the typographical error in eq. (6) and rectified the formatting for ref [7

The Impact of Study Abroad on Post-graduation Job Search

Following the tradition of a case study, this capstone research investigates the experience of recent graduates of the City University of New York (CUNY) who participated in study abroad programs managed by the College of Staten Island (CSI) between Fall 2010 and Summer 2015 and examines their perceptions of the post-graduation job search process. The data was collected through an online survey of 72 CUNY graduates and interviews with four survey respondents. The research findings did not show that the employment rate of CUNY study abroad alumni were any better or worse than others. However, many alumni believed that their international experience helped or could help them to land a job regardless of the professions they were pursuing. The research results also suggest that CUNY study abroad alumni thought that “soft skills” such as communication skills, ability to work with others, problem-solving skills, adaptability, maturity, flexibility, independence, open-mindedness, motivation, and self-awareness gained through study abroad experience, rather than technical skills and knowledge such as language skills or academic and professional knowledge, helped them to get a job. They also felt that study abroad added a unique value to their resumes. The findings from this research support results from similar studies, which have been done in different institutional or cultural contexts in the past about the professional impact of the study abroad experience. It offers ideas for study abroad programming and advisement, as well as career advisement, so students can more efficiently gain those skills which can help them become more marketable job seekers and effectively use study abroad experience as a tool for career development

Metamorphic and geochemical signatures of calc-silicate gneisses from the Sawtooth Metamorphic Complex, Idaho, USA : implications for crustal evolution in western North America

The Sawtooth Metamorphic Complex (SMC) of central Idaho contains exposures of metasupracrustal rocks that may provide constraints on Precambrian crustal evolution in northwestern United States. Petrographic textures, whole-rock geochemistry, and thermobarmetry of SMC calc-silicate gneisses, collected at high-resolution, record multiple stages of crustal development, including: contiguous deposition of a sandstone-to-shale sequence derived from post-Archean continental sediments, metamorphism during two medium-high-grade thermal events (M1, M2), and two distinct episodes of deformation (D1, D2). Whole-rock concentrations of Cr (23.97-76.43 ± 3.0 ppm), Ni (6.82-33.10 ± 3.5 ppm), Th (2.11-12.04 ± 1.6 ppm), Sc (3.81-11.53 ± 1.6 ppm), and Zr (322-658 ± 3.9 ppm) in SMC cal-silicates are consistent with derivation from post-Archean, continental sources that have undergone sedimentary maturation and recycling typical of detritus deposited in passive-margin environments. Al-Ti-Zr ratios suggest calc-silicates represent a sequence of calcareous sandstones and marls, with bulk geochemical fluctuations reflecting varying proportions of clay and quartzo-feldspathic detritus. The sandstone-to-shale continuum may reflect a NW-to-SE, deep-to-shallow-water transition in the depositional environment of SMC calc-silicates. Temperature estimates for M1 and M2 are constrained by mineral thermometry and ten isobaric pseudosections. Peak metamorphic M1 conditions, characterized by the assemblage: cpx + qz + pl + kfs + phl + rt, are estimated at temperatures \u3e750-775ºC and oxygenated fluids (XO \u3e 0.35). M1 was followed by widespread D1 deformation at high P and T, resulting in deformation twinning in clinopyroxene. M2 occurred at conditions of ~550-725ºC and H2O-rich fluids (XCO2 ≈ 0.34), resulting in the diagnostic assemblage amph + kfs + qz+ cpx + pl + ttn. Undeformed, poikiloblastic amphiboles overprint deformation twins in clinopyroxene, suggesting M2 was a static, thermal event post-dating M1 and D1. Late-stage, brittle-ductile D2 deformation is characterized by mylonitic lenses of quartz, fractures within M1 clinopyroxenes that cross-cut and offset D2 deformation twins, and localized fracturing of M2 amphiboles. Geochemical signatures of SMC calc-silicates indicative of post-Archean, passive-margin, continental sediments are most consistent with associations with nearby Neoproterozoic and Mesoproterozoic strata, suggesting the SMC may record deposition and multiple metamorphic/deformation events along western Laurentia associated with development of the 1100-750 Ma supercontinent Rodinia

All Local Conserved Quantities of the One-Dimensional Hubbard Model

We present the exact expression for all the local conserved quantities of the one-dimensional Hubbard model. We identify the operator set constructing the local conserved quantities and find that nontrivial coefficients appear in the higher order charges newly obtained. We derive the recursion equation for these coefficients, and some of them are explicitly given. We also prove the local conserved quantities obtained in this work are complete.Comment: 7 pages, 3 figures for main text + 40 pages, 4 figures for supplemental material. The manuscript has been rewritten in fermion notation, and the proof of completeness has been removed and will be published separately with new result

Macrophage Models For Tuberculosis Studies, A Systematic Review And Meta-Analysis Study

Setting: Macrophage models create an environment for the growth of mycobacterium tuberculosis and can be applied to studies on the intracellular pathogen.Objective: To review macrophage models for tuberculosis studies in terms of the cell sources and applications.Methods: The online English database PubMed, Chinese databases such as CNKI, SinoMed, and Wanfang were searched up to December 2010 for published articles. Two groups of terms were used for the information retrieval, one of which includes macrophage model and macrophage; the other group of terms comprises mycobacterium tuberculosis. For PubMed, the two groups of English terms were applied, while for the Chinese databases, related Chinese terms were used.Results: Cell sources of macrophage models include murine bone marrows, human peripheral blood, human lungs, and cell lines. The screened antituberculosis drugs are Western drugs such as ciprofloxacin and ofloxacin, and traditional Chinese medications like pittosporum brevicalyx (oliv.) gagnep and Ranunculus ternatus thunb. The regulation of SigB and SigF was described in the pathogenesis of tuberculosis, while pknE mutant modifying the innate immune response in immuno-mechanism of tuberculosis.Conclusions: There are four major cell sources for developing a macrophage model, which can be applied to studies on screening both Western and Chinese anti-TB drugs, figuring out the pathogenesis and immune-mechanism of TB with some key issues remaining to be dealt with