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Yadav R, Poudyal S, Rajarapu R, Biswal B, Barman PK, Kasiviswanathan S, Novoselov KS, Misra A. Low Power Volatile and Nonvolatile Memristive Devices from 1D MoO 2-MoS 2 Core-Shell Heterostructures for Future Bio-Inspired Computing. Small 2024; 20:e2309163. [PMID: 38150637 DOI: 10.1002/smll.202309163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/05/2023] [Indexed: 12/29/2023]
Abstract
Memristors-based integrated circuits for emerging bio-inspired computing paradigms require an integrated approach utilizing both volatile and nonvolatile memristive devices. Here, an innovative architecture comprising of 1D CVD-grown core-shell heterostructures (CSHSs) of MoO2-MoS2 is employed as memristors manifesting both volatile switching (with high selectivity of 107 and steep slope of 0.6 mV decade-1) and nonvolatile switching phenomena (with Ion/Ioff ≈103 and switching speed of 60 ns). In these CSHSs, the metallic core MoO2 with high current carrying capacity provides a conformal and immaculate interface with semiconducting MoS2 shells and therefore it acts as a bottom electrode for the memristors. The power consumption in volatile devices is as low as 50 pW per set transition and 0.1 fW in standby mode. Voltage-driven current spikes are observed for volatile devices while with nonvolatile memristors, key features of a biological synapse such as short/long-term plasticity and paired pulse facilitation are emulated suggesting their potential for the development of neuromorphic circuits. These CSHSs offer an unprecedented solution for the interfacial issues between metallic electrodes and the layered materials-based switching element with the prospects of developing smaller footprint memristive devices for future integrated circuits.
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Affiliation(s)
- Renu Yadav
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Centre for 2D Materials Research and Innovation, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Saroj Poudyal
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Centre for 2D Materials Research and Innovation, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Ramesh Rajarapu
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Centre for 2D Materials Research and Innovation, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Bubunu Biswal
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Centre for 2D Materials Research and Innovation, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Prahalad Kanti Barman
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Centre for 2D Materials Research and Innovation, Indian Institute of Technology Madras, Chennai, 600036, India
| | - S Kasiviswanathan
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Kostya S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - Abhishek Misra
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Centre for 2D Materials Research and Innovation, Indian Institute of Technology Madras, Chennai, 600036, India
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Mudgal R, Jakhar A, Gupta P, Yadav RS, Biswal B, Sahu P, Bangar H, Kumar A, Chowdhury N, Satpati B, Kumar Nanda BR, Satpathy S, Das S, Muduli PK. Magnetic-Proximity-Induced Efficient Charge-to-Spin Conversion in Large-Area PtSe 2/Ni 80Fe 20 Heterostructures. Nano Lett 2023; 23:11925-11931. [PMID: 38088819 DOI: 10.1021/acs.nanolett.3c04060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
As a topological Dirac semimetal with controllable spin-orbit coupling and conductivity, PtSe2, a transition-metal dichalcogenide, is a promising material for several applications, from optoelectrics to sensors. However, its potential for spintronics applications has yet to be explored. In this work, we demonstrate that the PtSe2/Ni80Fe20 heterostructure can generate large damping-like current-induced spin-orbit torques (SOT), despite the absence of spin-splitting in bulk PtSe2. The efficiency of charge-to-spin conversion is found to be -0.1 ± 0.02 nm-1 in PtSe2/Ni80Fe20, which is 3 times that of the control sample, Ni80Fe20/Pt. Our band structure calculations show that the SOT due to PtSe2 arises from an unexpectedly large spin splitting in the interfacial region of PtSe2 introduced by the proximity magnetic field of the Ni80Fe20 layer. Our results open up the possibilities of using large-area PtSe2 for energy-efficient nanoscale devices by utilizing proximity-induced SOT.
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Affiliation(s)
- Richa Mudgal
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Alka Jakhar
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pankhuri Gupta
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Ram Singh Yadav
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Bubunu Biswal
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India
| | - Pratik Sahu
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Department of Physics & Astronomy, University of Missouri, Columbia, Missouri 65211, United States
| | - Himanshu Bangar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Akash Kumar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Department of Physics, University of Gothenburg, Gothenburg 412 96, Sweden
| | - Niru Chowdhury
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Biswarup Satpati
- Surface Physics & Material Science Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata 700064, India
| | - Birabar Ranjit Kumar Nanda
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sashi Satpathy
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India
- Department of Physics & Astronomy, University of Missouri, Columbia, Missouri 65211, United States
| | - Samaresh Das
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Rajarapu R, Barman PK, Yadav R, Biswas R, Devaraj M, Poudyal S, Biswal B, Laxmi V, Pradhan GK, Raghunathan V, Nayak PK, Misra A. Pulsed Carrier Gas Assisted High-Quality Synthetic 3 R-Phase Sword-like MoS 2: A Versatile Optoelectronic Material. ACS Nano 2022; 16:21366-21376. [PMID: 36468945 DOI: 10.1021/acsnano.2c09673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Synthesizing a material with the desired polymorphic phase in a chemical vapor deposition (CVD) process requires a delicate balance among various thermodynamic variables. Here, we present a methodology to synthesize rhombohedral (3R)-phase MoS2 in a well-defined sword-like geometry having lengths up to 120 μm, uniform width of 2-3 μm and thickness of 3-7 nm by controlling the carrier gas flow dynamics from continuous mode to pulsed mode during the CVD growth process. Characteristic signatures such as high degree of circular dichroism (∼58% at 100 K), distinct evolution of low-frequency Raman peaks and increasing intensity of second harmonic signals with increasing number of layers conclusively establish the 3R-phase of the material. A high value (∼844 pm/V) of second-order susceptibility for few-layer-thick MoS2 swords signifies the potential of MoS2 to serve as an atomically thin nonlinear medium. A field effect mobility of 40 cm2/V-s and Ion/Ioff ratio of ∼106 further confirm the electronic-grade standard of this 3R-phase MoS2. These findings are significant for the development of emerging quantum electronic devices utilizing valley-based physics and nonlinear optical phenomena in layered materials.
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Affiliation(s)
- Ramesh Rajarapu
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Prahalad Kanti Barman
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Renu Yadav
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Rabindra Biswas
- Department of Electrical Communication Engineering, Indian Institution of Science, Bangalore- 560012, India
| | - Manikandan Devaraj
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- Micro Nano and Bio-Fluidics Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Saroj Poudyal
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Bubunu Biswal
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Vijay Laxmi
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Gopal K Pradhan
- Department of Physics, School of Applied Sciences, KIIT Deemed to be University, Bhubaneswar, Odisha-751024, India
| | - Varun Raghunathan
- Department of Electrical Communication Engineering, Indian Institution of Science, Bangalore- 560012, India
| | - Pramoda K Nayak
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
- Micro Nano and Bio-Fluidics Group, Indian Institute of Technology Madras, Chennai-600036, India
| | - Abhishek Misra
- Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India
- 2D Materials Research and Innovation Group, Indian Institute of Technology Madras, Chennai-600036, India
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Nayak AK, Biswal B, Sudheer KP. Drought hotspot maps and regional drought characteristics curves: Development of a novel framework and its application to an Indian River basin undergoing climatic changes. Sci Total Environ 2022; 807:151083. [PMID: 34757103 DOI: 10.1016/j.scitotenv.2021.151083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/28/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
Drought is one of the significant natural disasters that incurs billion dollars of economic damage every year. Among all, agricultural drought needs critical attention for drought monitoring due to its direct effect on crop yield and management of irrigation water. Most of the previous studies focused on regionalizing drought using k-means, hierarchal, fuzzy, and entropy-based clustering techniques. However, these techniques are not suitable where the clusters are not separated distinctively, and the number of clusters cannot be estimated automatically. In this study, we have developed agricultural drought hotspot maps using Soil moisture deficit index (SMDI) and the regional severity (S), duration (D), and frequency (F) curves using complex network algorithm for the future warming climate (2041-2070) of the Mahanadi River basin (MRB) in India. We have used a modified dynamic Budyko (DB) hydrological model to simulate daily soil moisture at a spatial scale of 0.25° × 0.25° using input from four GCMs for the RCP 4.5 scenario. The modified DB model was calibrated and validated for the study area. The model proved to be capable of simulating the soil moisture dynamics over the basin and also effectively captured the historical droughts occurred in the basin. The drought hotspot maps of the basin suggest that the northern, south-eastern, and central parts of the basins are going to experience more number of droughts. The results suggest that for most of the clusters, the regional S-D-F curve can be utilized to understand the future drought characteristics at site-specific as well as regional scale, as the confidence band is found to be very narrow. Overall, our study provides a framework to develop regional S-D-F curve.
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Affiliation(s)
- A K Nayak
- Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - B Biswal
- Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - K P Sudheer
- Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, India; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN, USA.
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Dora C, Patro R, Rout S, Biswal P, Biswal B. Adaptive SSA Based Muscle Artifact Removal from Single Channel EEG Using Neural Network Regressor. Ing Rech Biomed 2021. [DOI: 10.1016/j.irbm.2020.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tik M, Hoffmann A, Sladky R, Tomova L, Hummer A, de Lara LN, Biswal B, Bukowski H, Pripfl J, Lamm C, Windischberger C. P107 Assessing effectiveness and specificity of DLPFC rTMS using an unbiased resting-state approach. Clin Neurophysiol 2017. [DOI: 10.1016/j.clinph.2016.10.231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mishra N, Hasse M, Biswal B, Singh HP. Reliability of unstable periodic orbit based control strategies in biological systems. Chaos 2015; 25:043104. [PMID: 25933652 DOI: 10.1063/1.4916899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Presence of recurrent and statistically significant unstable periodic orbits (UPOs) in time series obtained from biological systems is now routinely used as evidence for low dimensional chaos. Extracting accurate dynamical information from the detected UPO trajectories is vital for successful control strategies that either aim to stabilize the system near the fixed point or steer the system away from the periodic orbits. A hybrid UPO detection method from return maps that combines topological recurrence criterion, matrix fit algorithm, and stringent criterion for fixed point location gives accurate and statistically significant UPOs even in the presence of significant noise. Geometry of the return map, frequency of UPOs visiting the same trajectory, length of the data set, strength of the noise, and degree of nonstationarity affect the efficacy of the proposed method. Results suggest that establishing determinism from unambiguous UPO detection is often possible in short data sets with significant noise, but derived dynamical properties are rarely accurate and adequate for controlling the dynamics around these UPOs. A repeat chaos control experiment on epileptic hippocampal slices through more stringent control strategy and adaptive UPO tracking is reinterpreted in this context through simulation of similar control experiments on an analogous but stochastic computer model of epileptic brain slices. Reproduction of equivalent results suggests that far more stringent criteria are needed for linking apparent success of control in such experiments with possible determinism in the underlying dynamics.
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Affiliation(s)
- Nagender Mishra
- Department of Physics & Astrophysics, University of Delhi, Delhi 110007, India
| | - Maria Hasse
- Institut für Höchstleistungsrechnen, Universität Stuttgart, D-70569 Stuttgart, Germany
| | - B Biswal
- Cluster Innovation Center, University of Delhi, Delhi 110007, India
| | - Harinder P Singh
- Department of Physics & Astrophysics, University of Delhi, Delhi 110007, India
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Biswal B, Mishra S, Biswal P, Prabhakar T. Detection and power quality disturbance classification based on wavelet packet decomposition and modified immune optimization algorithm. KES 2012. [DOI: 10.3233/kes-2012-00248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- B. Biswal
- GMR Institute of Technology, Rajam, Srikakulam (Dist.), India
| | - S. Mishra
- Indian Institute of Technology, New Delhi, India
| | - P.K. Biswal
- International Institute of Information Technology, Bhubaneswar, Odisha, India
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Biswal B, Biswal M, Dash P, Mishra S. Time frequency analysis and power signal disturbance classification using support vector machine and differential evolution algorithm. KES 2012. [DOI: 10.3233/kes-2012-0243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- B. Biswal
- GMR Institute of Technology, Rajam, Srikakulam (Dist.), India
| | - M.K. Biswal
- Silicon Institute of Technology, Bhubaneswar, India
| | - P.K. Dash
- S'O'A University, Bhubaneswar, India
| | - S. Mishra
- Indian Institute of Technology, Delhi, India
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Biswal B, Held RJ, Khanna V, Wang J, Hilfer R. Towards precise prediction of transport properties from synthetic computer tomography of reconstructed porous media. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:041301. [PMID: 19905302 DOI: 10.1103/physreve.80.041301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Indexed: 05/28/2023]
Abstract
Transport properties of a multiscale carbonate rock are predicted from pore scale models, reconstructed using a continuum geometrical modeling technique. The method combines crystallite information from two-dimensional high-resolution images with sedimentary correlations from a three-dimensional low-resolution microcomputed tomography ( micro-CT) image to produce a rock sample with calibrated porosity, structural correlation, and transport properties at arbitrary resolutions. Synthetic micro-CT images of the reconstructed model match well with experimental micro-CT images at different resolutions, making it possible to predict physical transport parameters at higher resolutions.
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Affiliation(s)
- B Biswal
- ICP, Universität Stuttgart, Pfaffenwaldring 27, 70569 Stuttgart, Germany
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Affiliation(s)
- B. Biswal
- Silicon Institute of Technology, Silicon Hills, Patia, Bhubaneswar-751024, Orissa, India
| | - P.K. Dash
- Silicon Institute of Technology, Bhubaneswar, Orissa, India
| | - S. Mishra
- Centurian Institute of Technology, Bhubaneswar, Orissa, India
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Mennes M, Kelly AMC, Di Martino A, Shehzad Z, Biswal B, Castellanos FX, Milham MP. Functional Connectivity at Rest Predicts BOLD Activity During a Cognitive Task. Neuroimage 2009. [DOI: 10.1016/s1053-8119(09)70604-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Lin W, Zhu Q, Gao W, Chen Y, Toh CH, Styner M, Gerig G, Smith JK, Biswal B, Gilmore JH. Functional connectivity MR imaging reveals cortical functional connectivity in the developing brain. AJNR Am J Neuroradiol 2008; 29:1883-9. [PMID: 18784212 DOI: 10.3174/ajnr.a1256] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Unlike conventional functional MR imaging where external sensory/cognitive paradigms are needed to specifically activate different regions of the brain, resting functional connectivity MR imaging acquires images in the absence of cognitive demands (a resting condition) and detects brain regions, which are highly temporally correlated. Therefore, resting functional MR imaging is highly suited for the study of brain functional development in pediatric subjects. This study aimed to determine the temporal and spatial patterns of rfc in healthy pediatric subjects between 2 weeks and 2 years of age. MATERIALS AND METHODS Rfc studies were performed on 85 children: 38 neonates (2-4 weeks of age), 26 one-year-olds, and 21 two-year-olds. All subjects were imaged while asleep; no sedation was used. Six regions of interest were chosen, including the primary motor, sensory, and visual cortices in each hemisphere. Mean signal intensity of each region of interest was used to perform correlation analysis pixel by pixel throughout the entire brain, identifying regions with high temporal correlation. RESULTS Functional connectivity was observed in all subjects in the sensorimotor and visual areas. The percent brain volume exhibiting rfc and the strength of rfc continued to increase from 2 weeks to 2 years. The growth trajectories of the percent brain volume of rfc appeared to differ between the sensorimotor and visual areas, whereas the z-score was similar. The percent brain volume of rfc in the sensorimotor area was significantly larger than that in the visual area for subjects 2 weeks of age (P = .008) and 1-year-olds (P = .017) but not for the 2-year-olds. CONCLUSIONS These findings suggest that rfc in the sensorimotor precedes that in the visual area from 2 weeks to 1 year but becomes comparable at 2 years. In contrast, the comparable z-score values between the sensorimotor and visual areas for all age groups suggest a disassociation between percent brain volume and the strength of cortical rfc.
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Affiliation(s)
- W Lin
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Di Martino A, Scheres A, Margulies DS, Kelly AMC, Uddin LQ, Shehzad Z, Biswal B, Walters JR, Castellanos FX, Milham MP. Functional connectivity of human striatum: a resting state FMRI study. Cereb Cortex 2008; 18:2735-47. [PMID: 18400794 DOI: 10.1093/cercor/bhn041] [Citation(s) in RCA: 830] [Impact Index Per Article: 51.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Classically regarded as motor structures, the basal ganglia subserve a wide range of functions, including motor, cognitive, motivational, and emotional processes. Consistent with this broad-reaching involvement in brain function, basal ganglia dysfunction has been implicated in numerous neurological and psychiatric disorders. Despite recent advances in human neuroimaging, models of basal ganglia circuitry continue to rely primarily upon inference from animal studies. Here, we provide a comprehensive functional connectivity analysis of basal ganglia circuitry in humans through a functional magnetic resonance imaging examination during rest. Voxelwise regression analyses substantiated the hypothesized motor, cognitive, and affective divisions among striatal subregions, and provided in vivo evidence of a functional organization consistent with parallel and integrative loop models described in animals. Our findings also revealed subtler distinctions within striatal subregions not previously appreciated by task-based imaging approaches. For instance, the inferior ventral striatum is functionally connected with medial portions of orbitofrontal cortex, whereas a more superior ventral striatal seed is associated with medial and lateral portions. The ability to map multiple distinct striatal circuits in a single study in humans, as opposed to relying on meta-analyses of multiple studies, is a principal strength of resting state functional magnetic resonance imaging. This approach holds promise for studying basal ganglia dysfunction in clinical disorders.
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Affiliation(s)
- A Di Martino
- Phyllis Green and Randolph Cowen Institute for Pediatric Neuroscience, NYU Child Study Center, New York, NY 10016, USA
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Biswal B, Oren PE, Held RJ, Bakke S, Hilfer R. Stochastic multiscale model for carbonate rocks. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:061303. [PMID: 17677251 DOI: 10.1103/physreve.75.061303] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Indexed: 05/16/2023]
Abstract
A multiscale model for the diagenesis of carbonate rocks is proposed. It captures important pore scale characteristics of carbonate rocks: wide range of length scales in the pore diameters; large variability in the permeability; and strong dependence of the geometrical and transport parameters on the resolution. A pore scale microstructure of an oolithic dolostone with generic diagenetic features is successfully generated. The continuum representation of a reconstructed cubic sample of side length 2mm contains roughly 42 x 10{6} crystallites and pore diameters varying over many decades. Petrophysical parameters are computed on discretized samples of sizes up to 1000{3}. The model can be easily adapted to represent the multiscale microstructure of a wide variety of carbonate rocks.
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Affiliation(s)
- B Biswal
- ICP, Universität Stuttgart, Pfaffenwaldring 27, 70569 Stuttgart, Germany
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Abstract
There is a rapidly growing literature using fMRI technology to investigate the various forms of behavioral impairment associated with brain injury and disease. Given this, surprisingly little work has been conducted to examine the influence of neuropathophysiological processes on the fMRI signal. This paper reviews the literature examining baseline alteration in cerebrovascular parameters associated with normal aging, brain injury, and brain disease. In addition, findings from three cases of individuals with severe brain trauma will be presented to show the influence of brain trauma on baseline cerebrovascular parameters measured by fMRI. The methods used here can be implemented by other investigators to accurately isolate specific hemodynamic changes that can influence the BOLD fMRI signal.
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Affiliation(s)
- F G Hillary
- Psychology Department, Pennsylvania State University, State College, PA , USA.
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Pradhan MK, Joshi PN, Nair JS, Ramaswamy NK, Iyer RK, Biswal B, Biswal UC. UV-B exposure enhances senescence of wheat leaves: Modulation by photosynthetically active radiation. Radiat Environ Biophys 2006; 45:221-9. [PMID: 16850336 DOI: 10.1007/s00411-006-0055-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 06/19/2006] [Indexed: 05/10/2023]
Abstract
The alterations in structure and function of photosystem II (PS II) during the senescence of primary leaves of wheat seedlings have been compared with the changes induced by ultraviolet-B (UV-B) radiation in the presence or absence of photosynthetically active radiation (PAR). The results indicated that the senescence-induced loss in pigment content, thylakoid membrane integrity and carotenoid-to-chlorophyll (Car-to-Chl) energy transfer efficiency was intensified by exposure to UV-B radiation. Different parameters for the measurement of PS II activity, such as Chl a fluorescence, O2-evolution and thermoluminescence intensity, were altered during senescence and these alterations were furthered by UV-B irradiation. The damage of photosynthetic apparatus by UV-B exposure in the presence of PAR was less than the damage in absence of PAR. The activation of molecular defense mechanisms could be a factor in the alleviation of UV-B damage in the presence of PAR.
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Affiliation(s)
- M K Pradhan
- Anchal College, Padampur P O: Rajborasambar, 768036 Bargarh, Orissa, India
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Biswal B, Shah N, Shah N, Trivedi M, Nayak S, Dave H. Automatic segmentation of pancreatic images using ISODATA alorithm. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.14149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
14149 Background: Pancreatic cancer is the second most common gastrointestinal malignancy in the United States, where it ranks 4th among all deaths caused by cancers. Early detection of pancreatic cancer remains a challange. Methods: MR images with different T1 and T2 weighting from the anatomical regions with the same imaging parameters were obtained. ISODATA segmentation algorithm, a multivariate method was used to reliable detect the various clusters in the data sets. Results: In all the four subjects, the pancreatic region was found to be from a different (and unique) cluster. This cluster covered the pancreatic region in all the four subjects. Conclusions: The ISODATA algorithm presented could detect the pancreatic region without manual tracing. No significant financial relationships to disclose.
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Affiliation(s)
- B. Biswal
- University of Medicine and Dentistry of New Jersey, Newark, NJ; Teleprime, Schaumburg, IL; Georgetown University, Washington, DC
| | - N. Shah
- University of Medicine and Dentistry of New Jersey, Newark, NJ; Teleprime, Schaumburg, IL; Georgetown University, Washington, DC
| | - N. Shah
- University of Medicine and Dentistry of New Jersey, Newark, NJ; Teleprime, Schaumburg, IL; Georgetown University, Washington, DC
| | - M. Trivedi
- University of Medicine and Dentistry of New Jersey, Newark, NJ; Teleprime, Schaumburg, IL; Georgetown University, Washington, DC
| | - S. Nayak
- University of Medicine and Dentistry of New Jersey, Newark, NJ; Teleprime, Schaumburg, IL; Georgetown University, Washington, DC
| | - H. Dave
- University of Medicine and Dentistry of New Jersey, Newark, NJ; Teleprime, Schaumburg, IL; Georgetown University, Washington, DC
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Abstract
We demonstrate a technique for the enhancement of chaos in a computational model of a periodically stimulated excitable neuron. "Anticontrol" of chaos is achieved through intermittent adaptive intervention, which is based on finite-time Lyapunov exponents measured from the time series. Our results suggest that an adaptive strategy for chaos anticontrol is viable for increasing the complexity in physiological systems that are typically both noisy and nonstationary.
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Affiliation(s)
- Kopal Gupta
- Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India
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22
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Raval MK, Biswal B, Biswal UC. The mystery of oxygen evolution: analysis of structure and function of photosystem II, the water-plastoquinone oxido-reductase. Photosynth Res 2005; 85:267-93. [PMID: 16170631 DOI: 10.1007/s11120-005-8163-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Accepted: 05/26/2005] [Indexed: 05/04/2023]
Abstract
Photosystem II (PS II) of thylakoid membrane of photosynthetic organisms has drawn attention of researchers over the years because it is the only system on Earth that provides us with oxygen that we breathe. In the recent past, structure of PS II has been the focus of research in plant science. The report of X-ray crystallographic structure of PS II complex by the research groups of James Barber and So Iwata in UK is a milestone in the area of research in photosynthesis. It follows the pioneering and elegant work from the laboratories of Horst Witt and W. Saenger in Germany, and J. Shen in Japan. It is time to analyze the historic events during the long journey made by the researchers to arrive at this point. This review makes an attempt to critically review the growth of the advancement of concepts and knowledge on the photosystem in the background of technological development. We conclude the review with perspectives on research and technology that should reveal the complete story of PS II of thylakoid in the future.
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Affiliation(s)
- M K Raval
- P.G. Department of Chemistry, Government College, Sundargarh, Orissa, India.
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23
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James M, Biswal B, Wang M, Cherney M, Chan L, Yannopoulos C, Bilimoria D, Nicolas O, Bedard J. Non-nucleoside inhibitors of NS5B polymerase from HCV, genotypes 1b and 2a. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305097916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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24
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Hilfer R, Biswal B, Mattutis HG, Janke W. Multicanonical Monte Carlo study and analysis of tails for the order-parameter distribution of the two-dimensional Ising model. ACTA ACUST UNITED AC 2003; 68:046123. [PMID: 14683018 DOI: 10.1103/physreve.68.046123] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2003] [Indexed: 11/07/2022]
Abstract
The tails of the critical order-parameter distribution of the two-dimensional Ising model are investigated through extensive multicanonical Monte Carlo simulations. Results for fixed boundary conditions are reported here, and compared with known results for periodic boundary conditions. Clear numerical evidence for "fat" stretched exponential tails exists below the critical temperature, indicating the possible presence of fat tails at the critical temperature. Our work suggests that the true order-parameter distribution at the critical temperature must be considered to be unknown at present.
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Affiliation(s)
- R Hilfer
- ICA-1, Universität Stuttgart, Pfaffenwaldring 27, 70569 Stuttgart, Germany
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Nayak L, Biswal B, Ramaswamy NK, Iyer RK, Nair JS, Biswal UC. Ultraviolet-A induced changes in photosystem II of thylakoids: effects of senescence and high growth temperature. J Photochem Photobiol B 2003; 70:59-65. [PMID: 12849695 DOI: 10.1016/s1011-1344(03)00052-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Ultraviolet-A (UV-A) radiation induced changes in photosystem II (PS II) of senescing leaves of wheat seedlings were investigated. UV-A radiation did not show any significant effect on the level of photosynthetic pigments. However, the decline in F(v)/F(m) and oxygen evolution rate indicated the damaging effect of the radiation on primary photochemistry of PS II. Modification at the Q(B)-binding site was inferred from the observed downshift of peak temperature of thermoluminescence (TL) B-bands. The UV-A induced changes in PS II of chloroplasts from senescing leaves were found to be synergistically accelerated by high growth temperature.
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Affiliation(s)
- L Nayak
- School of Life Sciences, Sambalpur University, Jyoti Vihar, Sambalpur, India
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26
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Biswal B, Dasgupta C. Stochastic neural network model for spontaneous bursting in hippocampal slices. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 66:051908. [PMID: 12513524 DOI: 10.1103/physreve.66.051908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2002] [Indexed: 05/24/2023]
Abstract
A biologically plausible, stochastic, neural network model that exhibits spontaneous transitions between a low-activity (normal) state and a high-activity (epileptic) state is studied by computer simulation. Brief excursions of the network to the high-activity state lead to spontaneous population bursting similar to the behavior observed in hippocampal slices bathed in a high-potassium medium. Although the variability of interburst intervals in this model is due to stochasticity, first return maps of successive interburst intervals show trajectories that resemble the behavior expected near unstable periodic orbits (UPOs) of systems exhibiting deterministic chaos. Simulations of the effects of the application of chaos control, periodic pacing, and anticontrol to the network model yield results that are qualitatively similar to those obtained in experiments on hippocampal slices. Estimation of the statistical significance of UPOs through surrogate data analysis also leads to results that resemble those of similar analysis of data obtained from slice experiments and human epileptic activity. These results suggest that spontaneous population bursting in hippocampal slices may be a manifestation of stochastic bistable dynamics, rather than of deterministic chaos. Our results also question the reliability of some of the recently proposed, UPO-based, statistical methods for detecting determinism and chaos in experimental time-series data.
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Affiliation(s)
- B Biswal
- ICA1, University of Stuttgart, Pfaffenwaldring 27, Germany
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Biswal B, Dasgupta C. Neural network model for apparent deterministic chaos in spontaneously bursting hippocampal slices. Phys Rev Lett 2002; 88:088102. [PMID: 11863975 DOI: 10.1103/physrevlett.88.088102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2001] [Indexed: 05/23/2023]
Abstract
A neural network model that exhibits stochastic population bursting is studied by simulation. First return maps of interburst intervals exhibit recurrent unstable-periodic-orbit(UPO)-like trajectories similar to those found in experiments on hippocampal slices. Applications of various control methods and surrogate analysis for UPO detection also yield results similar to those of experiments. Our results question the interpretation of the experimental data as evidence for deterministic chaos and suggest caution in the use of UPO-based methods for detecting determinism in time-series data.
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Affiliation(s)
- B Biswal
- ICA1, University of Stuttgart, Pfaffenwaldring 27, D-70569 Stuttgart, Germany
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Abstract
Signal intensity changes in fMRI during rest caused by vasomotor fluctuations were investigated in this work. Resting-state baseline fluctuations were evaluated in 12 children anesthetized with thiopental. Five subjects had fluctuations related to subvoxel motion. In seven subjects without significant motion, slow signal fluctuation at 0.025-0.041 Hz near one or more primary sensory cortices was observed. In each subject the amplitude and frequency of the fluctuations were stable. It is hypothesized that thiopental, which reduces blood pressure and flow in the cortex, alters the feedback in neurovascular coupling leading to an increase in the magnitude and a reduction in the frequency of these fluctuations. The use of anesthesia in fMRI may provide new insight into neural connectivity and the coupling of blood flow and neural metabolism.
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Affiliation(s)
- V Kiviniemi
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland.
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Biswal B, Hasan QZ, Sharma K, Dutta N. Effect of Selective Consumption on Intake, Diet Selectivity and Passage Kinetics of Wheat Straw by Barbari Goats. Asian Australas J Anim Sci 2000. [DOI: 10.5713/ajas.2000.913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Li SJ, Biswal B, Li Z, Risinger R, Rainey C, Cho JK, Salmeron BJ, Stein EA. Cocaine administration decreases functional connectivity in human primary visual and motor cortex as detected by functional MRI. Magn Reson Med 2000; 43:45-51. [PMID: 10642730 DOI: 10.1002/(sici)1522-2594(200001)43:1<45::aid-mrm6>3.0.co;2-0] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Functional magnetic resonance imaging (fMRI) was conducted to observe the effects of cocaine administration on the physiological fluctuations of fMRI signal in two brain regions. Seven long-term cocaine users with an average age of 32 years and 8 years of cocaine use history were recruited for the study. A T2*-weighted fast echo-planar imaging (EPI) pulse sequence was employed at 1.5 T to acquire three sets of brain images for each subject under three conditions (at rest, after saline injection, and after cocaine injection [0.57 mg/kg]). Cross-correlation maps were constructed using the synchronous, low frequency signal from voxel time courses after filtering respiratory, cardiac, and other physiological noise. A quantitative evaluation of the changes in functional connectivity was made using spatial correlation coefficient (SCC) analysis. A marked 50% reduction in SCC values in the region of primary visual cortex and 43% reduction in SCC values in the region of primary motor cortex were observed after cocaine administration. This significant reduction in SCC values in these cortical regions is a reflection of changes in neuronal activity. It is suggested that the observed changes in low frequency components after acute cocaine administration during a resting, no-task situation may be used as a baseline reference source when assessing the effects of cocaine on task-driven activation or on mesolimbic dopamine pathways.
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Affiliation(s)
- S J Li
- Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226, USA.
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Affiliation(s)
- V Haughton
- Department of Radiology, Medical College of Wisconsin, Milwaukee, USA
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Biswal B, Ulmer JL, Krippendorf RL, Harsch HH, Daniels DL, Hyde JS, Haughton VM. Abnormal cerebral activation associated with a motor task in Tourette syndrome. AJNR Am J Neuroradiol 1998; 19:1509-12. [PMID: 9763386 PMCID: PMC8338689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND AND PURPOSE In Gilles de la Tourette syndrome, PET scanning and EEG suggest an abnormal organization of the sensorimotor cortex and basal ganglia. The purpose of this study was to use functional MR imaging to study activation in the sensorimotor cortex in patients with Tourette syndrome. METHODS From echo-planar images acquired during intermittent performance of a finger-tapping task, the location of activated pixels was determined by means of conventional signal processing methods. In five patients with Tourette syndrome and five healthy volunteers, the number of activated pixels in the sensorimotor cortices and supplementary motor areas were counted. The area over which the activation was distributed was calculated. RESULTS In the five patients, the average number of pixels activated during the finger-tapping task in the sensorimoter cortices and supplementary motor area (69.4 pixels) exceeded that in the volunteers (49.2 pixels). The difference was significant. The area over which the pixels was distributed was significantly larger (25.4 vs 13.8 cm2). CONCLUSION Motor function is organized differently in patients with Tourette syndrome than in healthy subjects.
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Affiliation(s)
- B Biswal
- Department of Biophysics, Medical College of Wisconsin, Milwaukee 53226, USA
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Biswal B, Hudetz AG, Yetkin FZ, Haughton VM, Hyde JS. Hypercapnia reversibly suppresses low-frequency fluctuations in the human motor cortex during rest using echo-planar MRI. J Cereb Blood Flow Metab 1997; 17:301-8. [PMID: 9119903 DOI: 10.1097/00004647-199703000-00007] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Using magnetic resonance (MR) echo-planar imaging (EPI), we recently demonstrated the presence of low-frequency fluctuations (< 0.1 Hz) in MR signal intensity from the resting human brain that have a high degree of temporal correlation (p < 10(-3)) within and across associated regions of the sensorimotor cortex. These fluctuations in MR signal intensity are believed to arise from fluctuations in capillary blood flow and oxygenation. A substantial overlap between the activation map generated by bilateral finger tapping and temporally-correlated voxels from the sensorimotor cortex obtained during rest was observed. In the work reported here, we investigated whether respiratory hypercapnia, which is known to suspend spontaneous oscillations in regional cerebral blood flow, influences these low-frequency fluctuations. The magnitude of low-frequency fluctuations was reversibly diminished during hypercapnia, resulting in a substantial decrease of the temporal correlation both within and across contralateral hemispheres of the sensorimotor cortex. After the breathing mixture was returned to ambient air, the magnitude and spatial extent of the temporal correlation of low-frequency fluctuations returned to normal. Results of this study support the hypothesis that low-frequency physiological fluctuations observed by MR in the human cortex and spontaneous flow oscillations observed in early studies by laser-Doppler flowmetry (LDF) in the cortex of the rat are identical and are secondary to fluctuations in neuronal activity.
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Affiliation(s)
- B Biswal
- Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226-0509, USA
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Abstract
Data obtained from functional magnetic resonance imaging are often limited by a low signal-to-noise ratio. The time-course data obtained from activated regions contain both system noise and physiological noise, primarily linked to the heart and respiratory rates, that are superimposed on task induced signals. Time averaging of a practical number of data sets is not very effective in improving the signal-to-noise ratio because neither system nor physiological noise is truly random. In this paper, a method is presented for filtering unwanted physiological fluctuations, including aliased signals that are formed as a result of long repetition time (TR) values. A pulse oximeter was used to obtain cardiac and respiratory information during the scanning period. Finite impulse response band-reject digital filters were designed to remove the physiological fluctuations. For comparison, cross-correlation analyses were performed at the same level of statistical significance on both filtered and unfiltered data. We demonstrate that this method can improve the detection of weak signals without increasing the probability of false positives.
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Affiliation(s)
- B Biswal
- Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226-0509, USA
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37
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Abstract
An MRI time course of 512 echo-planar images (EPI) in resting human brain obtained every 250 ms reveals fluctuations in signal intensity in each pixel that have a physiologic origin. Regions of the sensorimotor cortex that were activated secondary to hand movement were identified using functional MRI methodology (FMRI). Time courses of low frequency (< 0.1 Hz) fluctuations in resting brain were observed to have a high degree of temporal correlation (P < 10(-3)) within these regions and also with time courses in several other regions that can be associated with motor function. It is concluded that correlation of low frequency fluctuations, which may arise from fluctuations in blood oxygenation or flow, is a manifestation of functional connectivity of the brain.
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Affiliation(s)
- B Biswal
- Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226-0509, USA
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Joshi PN, Biswal B, Kulandaivelu G, Biswal UC. Response of senescing wheat leaves to ultraviolet A light: changes in energy transfer efficiency and PS II photochemistry. Radiat Environ Biophys 1994; 33:167-176. [PMID: 7938439 DOI: 10.1007/bf01219339] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Response of senescing leaves of wheat seedlings to ultraviolet A (UVA) radiation (365 nm) has been examined. The results indicate that senescence-induced disorganization of thylakoid membrane, decline in carotenoid-to-chlorophyll energy transfer, and enhancement of lipid peroxidation are furthered by radiation. The senescence-induced decline in photochemical activity of photosystem II further declines on irradiation. UVA does not specifically alter any site other than those damaged by senescence.
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Affiliation(s)
- P N Joshi
- Laboratory of Biophysics and Biochemistry, School of Life Sciences, Sambalpur University, Orissa, India
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Affiliation(s)
- B Biswal
- Department of Biochemistry, University of Wales, Aberystwyth, Penglais, Dyfed
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Abstract
We have studied the phosphorylation/dephosphorylation of several nuclear proteins in isolated nuclei from etiolated Avena seedlings as a function of red/far-red light. The effect of stimulatory (ADP-ribosylation by cholera toxin) or inhibitory (GDP beta S) conditions for GTP-binding proteins was also studied. Red or far-red light enhanced the phosphorylation level of 2 nuclear proteins with molecular masses of 75 and 60 kDa. The phosphorylation pattern was affected by the addition of cholera toxin or GDP beta S to the isolated nuclei. At least 2 proteins with molecular masses of 24 and 75 kDa cross-reacted by Western blot with GTP-binding protein antibodies.
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Affiliation(s)
- L C Romero
- Institute for Cellular and Molecular Photobiology, University of Nebraska, Lincoln 68588-0304
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Biswal B, Chowdhury D. Dimensionality dependence in the singular dynamic scaling in the dilute Ising model. Phys Rev A 1991; 43:4179-4181. [PMID: 9905517 DOI: 10.1103/physreva.43.4179] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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