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Varsi F, Ahmad S, Chakraborty M, Chandra A, Dugad SR, Goswami UD, Gupta SK, Hariharan B, Hayashi Y, Jagadeesan P, Jain A, Jain P, Kawakami S, Kojima H, Lipari P, Mahapatra S, Mohanty PK, Moharana R, Muraki Y, Nayak PK, Nonaka T, Oshima A, Pant BP, Pattanaik D, Paul S, Pradhan GS, Rameez M, Ramesh K, Reddy LV, Saha S, Sahoo R, Scaria R, Shibata S, Zuberi M. Evidence of a Hardening in the Cosmic Ray Proton Spectrum at around 166 TeV Observed by the GRAPES-3 Experiment. Phys Rev Lett 2024; 132:051002. [PMID: 38364164 DOI: 10.1103/physrevlett.132.051002] [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] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/16/2023] [Accepted: 01/04/2024] [Indexed: 02/18/2024]
Abstract
We present the measurement of the cosmic ray proton spectrum from 50 TeV to 1.3 PeV using 7.81×10^{6} extensive air shower events recorded by the ground-based GRAPES-3 experiment between 1 January 2014 and 26 October 2015 with a live time of 460 day. Our measurements provide an overlap with direct observations by satellite and balloon-based experiments. The electromagnetic and muon components in the shower were measured by a dense array of plastic scintillator detectors and a tracking muon telescope, respectively. The relative composition of the proton primary from the air shower data containing all primary particles was extracted using the multiplicity distribution of muons which is a sensitive observable for mass composition. The observed proton spectrum suggests a spectral hardening at ∼166 TeV and disfavors a single power law description of the spectrum up to the Knee energy (∼3 PeV).
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Affiliation(s)
- F Varsi
- Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - S Ahmad
- Aligarh Muslim University, Aligarh 202002, India
| | - M Chakraborty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - A Chandra
- Aligarh Muslim University, Aligarh 202002, India
| | - S R Dugad
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - U D Goswami
- Dibrugarh University, Dibrugarh 786004, India
| | - S K Gupta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - B Hariharan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Y Hayashi
- Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan
| | - P Jagadeesan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - A Jain
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - P Jain
- Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - S Kawakami
- Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan
| | - H Kojima
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - P Lipari
- INFN, Sezione Roma "Sapienza", Piazzale Aldo Moro 2, 00185 Roma, Italy
| | | | - P K Mohanty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - R Moharana
- Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Y Muraki
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya 464-8601, Japan
| | - P K Nayak
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - T Nonaka
- Institute for Cosmic Ray Research, Tokyo University, Kashiwa, Chiba 277-8582, Japan
| | - A Oshima
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - B P Pant
- Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - D Pattanaik
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Utkal University, Bhubaneswar 751004, India
| | - S Paul
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - G S Pradhan
- Indian Institute of Technology Indore, Indore 453552, India
| | - M Rameez
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - K Ramesh
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - L V Reddy
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - S Saha
- Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - R Sahoo
- Indian Institute of Technology Indore, Indore 453552, India
| | - R Scaria
- Indian Institute of Technology Indore, Indore 453552, India
| | - S Shibata
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - M Zuberi
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
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2
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Grassberger P, Dhar D, Mohanty PK. Many universality classes in an interface model restricted to non-negative heights. Phys Rev E 2023; 107:044112. [PMID: 37198813 DOI: 10.1103/physreve.107.044112] [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] [Received: 12/27/2022] [Accepted: 03/21/2023] [Indexed: 05/19/2023]
Abstract
We present a simple one-dimensional stochastic model with three control parameters and a surprisingly rich zoo of phase transitions. At each (discrete) site x and time t, an integer n(x,t) satisfies a linear interface equation with added random noise. Depending on the control parameters, this noise may or may not satisfy the detailed balance condition, so that the growing interfaces are in the Edwards-Wilkinson or in the Kardar-Parisi-Zhang universality class. In addition, there is also a constraint n(x,t)≥0. Points x where n>0 on one side and n=0 on the other are called "fronts." These fronts can be "pushed" or "pulled," depending on the control parameters. For pulled fronts, the lateral spreading is in the directed percolation (DP) universality class, while it is in a different universality class for pushed fronts, and another universality class in between. In the DP case, the activity at each active site can in general be arbitrarily large, in contrast to previous realizations of DP. Finally, we find two different types of transitions when the interface detaches from the line n=0 (with 〈n(x,t)〉→const on one side, and →∞ on the other), again with new universality classes. We also discuss a mapping of this model to the avalanche propagation in a directed Oslo rice pile model in specially prepared backgrounds.
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Affiliation(s)
- Peter Grassberger
- JSC, FZ Jülich, D-52425 Jülich, Germany
- MPI for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - Deepak Dhar
- Indian Institute of Science Education and Research, Dr. Homi Bhabah Road, Pune 411 008, India
| | - P K Mohanty
- Indian Institute of Science Education and Research, Mohanpur, Nadia 741 246, Kolkata, India
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3
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Kadam NR, Mohanty PK, Jain A. Protective Effect of Cucurbita maxima against Maximal Electroshock Induced Convulsions. JPRI 2021. [DOI: 10.9734/jpri/2021/v33i39a32146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the present investigation, an indigenous plant, Cucurbita maxima was studied for its protective effect against maximal electroshock (MES) induced convulsions in Wistar albino rats. The rats were pretreated with different doses (100, 200, 400 mg/kg) of hydroalcoholic extract of seeds of Cucurbita maxima for 14 days and then, they were subjected to maximal electroshock seizures (40 mA for 0.2 sec) treatment. Hydroalcoholic extract of Cucurbita maxima seeds at 200 and 400 mg/kg doses significantly reduced the duration of hind limb extension along with the protection of rats against maximal electroshock induced seizures. The reference standard i.e., phenytoin (20 mg/kg) provided complete protection. Thus, present study revealed anticonvulsant effect of Cucurbita maxima against maximal electroshock-induced convulsions in rats.
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Hariharan B, Chandra A, Dugad SR, Gupta SK, Jagadeesan P, Jain A, Mohanty PK, Morris SD, Nayak PK, Rakshe PS, Ramesh K, Rao BS, Reddy LV, Zuberi M, Hayashi Y, Kawakami S, Ahmad S, Kojima H, Oshima A, Shibata S, Muraki Y, Tanaka K. Measurement of the Electrical Properties of a Thundercloud Through Muon Imaging by the GRAPES-3 Experiment. Phys Rev Lett 2019; 122:105101. [PMID: 30932668 DOI: 10.1103/physrevlett.122.105101] [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] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 01/21/2019] [Indexed: 06/09/2023]
Abstract
The GRAPES-3 muon telescope located in Ooty, India records rapid (∼10 min) variations in the muon intensity during major thunderstorms. Out of a total of 184 thunderstorms recorded during the interval of April 2011-December 2014, the one on December 1, 2014 produced a massive potential of 1.3 GV. The electric field measured by four well-separated (up to 6 km) monitors on the ground was used to help estimate some of the properties of this thundercloud, including its altitude and area that were found to be 11.4 km above mean sea level and ≥380 km^{2}, respectively. A charging time of 6 min to reach 1.3 GV implied the delivery of a power of ≥2 GW by this thundercloud that was moving at a speed of ∼60 km h^{-1}. This work possibly provides the first direct evidence for the generation of gigavolt potentials in thunderclouds that could also possibly explain the production of highest-energy (100 MeV) gamma rays in the terrestrial gamma-ray flashes.
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Affiliation(s)
- B Hariharan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - A Chandra
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - S R Dugad
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - S K Gupta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - P Jagadeesan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - A Jain
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - P K Mohanty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - S D Morris
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - P K Nayak
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - P S Rakshe
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - K Ramesh
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - B S Rao
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - L V Reddy
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - M Zuberi
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
| | - Y Hayashi
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- Graduate School of Science, Osaka City University, Osaka 558-8585, Japan
| | - S Kawakami
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- Graduate School of Science, Osaka City University, Osaka 558-8585, Japan
| | - S Ahmad
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- Aligarh Muslim University, Aligarh 202002, India
| | - H Kojima
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - A Oshima
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - S Shibata
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - Y Muraki
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Aichi 446-8601, Japan
| | - K Tanaka
- Cosmic Ray Laboratory, Raj Bhavan, Ooty 643001, India
- Graduate School of Information Sciences, Hiroshima City University, Hiroshima 731-3194, Japan
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5
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Abstract
Driven particles in the presence of crowded environment, obstacles, or kinetic constraints often exhibit negative differential mobility (NDM) due to their decreased dynamical activity. Based on the empirical studies of conserved lattice gas model, two species exclusion model and other interacting particle systems we propose a new mechanism for complex many-particle systems where slowing down of certain non-driven degrees of freedom by the external field can give rise to NDM. To prove that the slowing down of the non-driven degrees is indeed the underlying cause, we consider several driven diffusive systems including two species exclusion models, misanthrope process, and show from the exact steady state results that NDM indeed appears when some non-driven modes are slowed down deliberately. For clarity, we also provide a simple pedagogical example of two interacting random walkers on a ring which conforms to the proposed scenario.
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Affiliation(s)
- Amit Kumar Chatterjee
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - Urna Basu
- LPTMS, CNRS, Universitè Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
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Abstract
Conserved lattice-gas models in one dimension exhibit absorbing state phase transition (APT) with simple integer exponents β=1=ν=η, whereas the same on a ladder belong to directed percolation (DP) universality. We conjecture that additional stochasticity in particle transfer is a relevant perturbation and its presence on a ladder forces the APT to be in the DP class. To substantiate this we introduce a class of restricted conserved lattice-gas models on a multichain system (M×L square lattice with periodic boundary condition in both directions), where particles which have exactly one vacant neighbor are active and they move deterministically to the neighboring vacant site. We show that for odd number of chains, in the thermodynamic limit L→∞, these models exhibit APT at ρ_{c}=1/2(1+1/M) with β=1. On the other hand, for even-chain systems transition occurs at ρ_{c}=1/2 with β=1,2 for M=2,4, respectively, and β=3 for M≥6. We illustrate this unusual critical behavior analytically using a transfer-matrix method.
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Affiliation(s)
- Arijit Chatterjee
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
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Khan N, Sarkar P, Midya A, Mandal P, Mohanty PK. Continuously Varying Critical Exponents Beyond Weak Universality. Sci Rep 2017; 7:45004. [PMID: 28327622 PMCID: PMC5361157 DOI: 10.1038/srep45004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 02/14/2017] [Indexed: 11/09/2022] Open
Abstract
Renormalization group theory does not restrict the form of continuous variation of critical exponents which occurs in presence of a marginal operator. However, the continuous variation of critical exponents, observed in different contexts, usually follows a weak universality scenario where some of the exponents (e.g., β, γ, ν) vary keeping others (e.g., δ, η) fixed. Here we report ferromagnetic phase transition in (Sm1−yNdy)0.52Sr0.48MnO3 (0.5 ≤ y ≤ 1) single crystals where all three exponents β, γ, δ vary with Nd concentration y. Such a variation clearly violates both universality and weak universality hypothesis. We propose a new scaling theory that explains the present experimental results, reduces to the weak universality as a special case, and provides a generic route leading to continuous variation of critical exponents and multi-criticality.
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Affiliation(s)
- N Khan
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - P Sarkar
- Department of Physics, Serampore College, Serampore 712201, India
| | - A Midya
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - P Mandal
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
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8
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Abstract
We study diffusion of hard-core particles on a one-dimensional periodic lattice subjected to a constraint that the separation between any two consecutive particles does not increase beyond a fixed value n+1; an initial separation larger than n+1 can however decrease. These models undergo an absorbing state phase transition when the conserved particle density of the system falls below a critical threshold ρ_{c}=1/(n+1). We find that the ϕ_{k}, the density of 0-clusters (0 representing vacancies) of size 0≤k<n, vanish at the transition point along with activity density ρ_{a}. The steady state of these models can be written in matrix product form to obtain analytically the static exponents β_{k}=n-k and ν=1=η corresponding to each ϕ_{k}. We also show from numerical simulations that, starting from a natural condition, ϕ_{k}(t)s decay as t^{-α_{k}} with α_{k}=(n-k)/2 even though other dynamic exponents ν_{t}=2=z are independent of k; this ensures the validity of scaling laws β=αν_{t} and ν_{t}=zν.
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Affiliation(s)
- Arijit Chatterjee
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhan Nagar, Kolkata 700064, India
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9
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Bhattacherjee A, Mohanty PK, Mallik BK, Nanda S, Munda J. Comparative Blood Cell Morphometry and Differential Leukocyte Count of Two Breeds of Turkey, <i>Meleagris gallopavo</i> (Linnaeus, 1758). CURR SCI INDIA 2017. [DOI: 10.18520/cs/v112/i01/164-168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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10
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Mohanty PK, Arunbabu KP, Aziz T, Dugad SR, Gupta SK, Hariharan B, Jagadeesan P, Jain A, Morris SD, Rao BS, Hayashi Y, Kawakami S, Oshima A, Shibata S, Raha S, Subramanian P, Kojima H. Transient Weakening of Earth's Magnetic Shield Probed by a Cosmic Ray Burst. Phys Rev Lett 2016; 117:171101. [PMID: 27824449 DOI: 10.1103/physrevlett.117.171101] [Citation(s) in RCA: 2] [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: 06/16/2016] [Indexed: 06/06/2023]
Abstract
The GRAPES-3 tracking muon telescope in Ooty, India measures muon intensity at high cutoff rigidities (15-24 GV) along nine independent directions covering 2.3 sr. The arrival of a coronal mass ejection on 22 June 2015 18:40 UT had triggered a severe G4-class geomagnetic storm (storm). Starting 19:00 UT, the GRAPES-3 muon telescope recorded a 2 h high-energy (∼20 GeV) burst of galactic cosmic rays (GCRs) that was strongly correlated with a 40 nT surge in the interplanetary magnetic field (IMF). Simulations have shown that a large (17×) compression of the IMF to 680 nT, followed by reconnection with the geomagnetic field (GMF) leading to lower cutoff rigidities could generate this burst. Here, 680 nT represents a short-term change in GMF around Earth, averaged over 7 times its volume. The GCRs, due to lowering of cutoff rigidities, were deflected from Earth's day side by ∼210° in longitude, offering a natural explanation of its night-time detection by the GRAPES-3. The simultaneous occurrence of the burst in all nine directions suggests its origin close to Earth. It also indicates a transient weakening of Earth's magnetic shield, and may hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth, and endanger the lives of the astronauts in space.
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Affiliation(s)
- P K Mohanty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - K P Arunbabu
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - T Aziz
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - S R Dugad
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - S K Gupta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - B Hariharan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - P Jagadeesan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - A Jain
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - S D Morris
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - B S Rao
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India†
| | - Y Hayashi
- Graduate School of Science, Osaka City University, 558-8585 Osaka, Japan†
| | - S Kawakami
- Graduate School of Science, Osaka City University, 558-8585 Osaka, Japan†
| | - A Oshima
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan†
| | - S Shibata
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan†
| | - S Raha
- Bose Institute, 93/1, A.P.C. Road, Kolkata 700009, India†
| | - P Subramanian
- Indian Institute of Science Education and Research, Pune 411021, India†
| | - H Kojima
- Faculty of Engineering, Aichi Institute of Technology, Toyota City, Aichi 470-0392, Japan†
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11
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Abstract
Context— Active substance abuse is widely accepted as a contraindication for heart transplantation because of the theory that relapse would occur after transplantation and result in compromise of graft function, lowering long-term survival. Listing “recovering” substance abusers for heart transplantation has been controversial. Objective— To determine if substance abuse plays an unfavorable role in the outcome of heart transplantation. Methods— The medical records of all patients at our center who received a heart transplant more than 10 years ago were retrospectively reviewed for history of substance abuse. Results— From a pool of 189 transplant recipients, 47 patients had a definite history of substance abuse (group 1) and were considered in recovery, whereas 142 patients were clearly without any history of substance abuse (group 2). Group 1 had a significantly greater percentage of patients with a pretransplantation diagnosis of idiopathic cardiomyopathy ( P=.003), a higher occurrence of heart-related cause of death ( P=.017), and a significant prevalence of noncompliance ( P=.0001) and death because of noncompliance ( P=.0004). In contrast, group 2 surprisingly had a significantly higher incidence of death related to infection ( P=.0062), which is unexplained. Despite higher incidence of noncompliance in group 1, there was no significant difference in the overall survival rate between the 2 groups. Conclusion— These results suggest that patients with a history of substance abuse can undergo successful heart transplantation with acceptable long-term survival, though they are at greater risk for substance abuse relapse and resulting noncompliance with the treatment regimen. The extent to which relapse of substance abuse and its consequences affect the cost of posttransplantation care remains to be determined.
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Affiliation(s)
- J S Hanrahan
- McGuire Veterans Affairs Medical Center, Richmond, Va., USA
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12
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Abstract
We present simulations of the one-dimensional Oslo rice pile model in which the critical height at each site is randomly reset after each toppling. We use the fact that the stationary state of this sand-pile model is hyperuniform to reach system of sizes >10^{7}. Most previous simulations were seriously flawed by important finite-size corrections. We find that all critical exponents have values consistent with simple rationals: ν=4/3 for the correlation length exponent, D=9/4 for the fractal dimension of avalanche clusters, and z=10/7 for the dynamical exponent. In addition, we relate the hyperuniformity exponent to the correlation length exponent ν. Finally, we discuss the relationship with the quenched Edwards-Wilkinson model, where we find in particular that the local roughness exponent is α_{loc}=1.
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Affiliation(s)
| | - Deepak Dhar
- Tata Institute for Fundamental Research, Mumbai, India
| | - P K Mohanty
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Kolkata, India
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13
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Chatterjee AK, Daga B, Mohanty PK. Phase coexistence and spatial correlations in reconstituting k-mer models. Phys Rev E 2016; 94:012121. [PMID: 27575091 DOI: 10.1103/physreve.94.012121] [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] [Received: 05/17/2016] [Indexed: 06/06/2023]
Abstract
In reconstituting k-mer models, extended objects that occupy several sites on a one-dimensional lattice undergo directed or undirected diffusion, and reconstitute-when in contact-by transferring a single monomer unit from one k-mer to the other; the rates depend on the size of participating k-mers. This polydispersed system has two conserved quantities, the number of k-mers and the packing fraction. We provide a matrix product method to write the steady state of this model and to calculate the spatial correlation functions analytically. We show that for a constant reconstitution rate, the spatial correlation exhibits damped oscillations in some density regions separated, from other regions with exponential decay, by a disorder surface. In a specific limit, this constant-rate reconstitution model is equivalent to a single dimer model and exhibits a phase coexistence similar to the one observed earlier in totally asymmetric simple exclusion process on a ring with a defect.
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Affiliation(s)
- Amit Kumar Chatterjee
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics,1/AF Bidhan Nagar, Kolkata 700064, India
| | - Bijoy Daga
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics,1/AF Bidhan Nagar, Kolkata 700064, India
| | - P K Mohanty
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics,1/AF Bidhan Nagar, Kolkata 700064, India
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Das A, Chatterjee S, Pradhan P, Mohanty PK. Additivity property and emergence of power laws in nonequilibrium steady states. Phys Rev E 2015; 92:052107. [PMID: 26651647 DOI: 10.1103/physreve.92.052107] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Indexed: 11/07/2022]
Abstract
We show that an equilibriumlike additivity property can remarkably lead to power-law distributions observed frequently in a wide class of out-of-equilibrium systems. The additivity property can determine the full scaling form of the distribution functions and the associated exponents. The asymptotic behavior of these distributions is solely governed by branch-cut singularity in the variance of subsystem mass. To substantiate these claims, we explicitly calculate, using the additivity property, subsystem mass distributions in a wide class of previously studied mass aggregation models as well as in their variants. These results could help in the thermodynamic characterization of nonequilibrium critical phenomena.
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Affiliation(s)
- Arghya Das
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098, India
| | - Sayani Chatterjee
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098, India
| | - Punyabrata Pradhan
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098, India
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India.,Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
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Chatterjee A, Pradhan P, Mohanty PK. Cluster-factorized steady states in finite-range processes. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:032103. [PMID: 26465422 DOI: 10.1103/physreve.92.032103] [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] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Indexed: 06/05/2023]
Abstract
We study a class of nonequilibrium lattice models on a ring where particles hop in a particular direction, from a site to one of its (say, right) nearest neighbors, with a rate that depends on the occupation of all the neighboring sites within a range R. This finite-range process (FRP) for R=0 reduces to the well-known zero-range process (ZRP), giving rise to a factorized steady state (FSS) for any arbitrary hop rate. We show that, provided the hop rates satisfy a specific condition, the steady state of FRP can be written as a product of a cluster-weight function of (R+1) occupation variables. We show that, for a large class of cluster-weight functions, the cluster-factorized steady state admits a finite dimensional transfer-matrix formulation, which helps in calculating the spatial correlation functions and subsystem mass distributions exactly. We also discuss a criterion for which the FRP undergoes a condensation transition.
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Affiliation(s)
- Amit Chatterjee
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India
| | - Punyabrata Pradhan
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, India
| | - P K Mohanty
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, D-01187 Dresden, Germany
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Chatterjee S, Pradhan P, Mohanty PK. Zeroth law and nonequilibrium thermodynamics for steady states in contact. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:062136. [PMID: 26172690 DOI: 10.1103/physreve.91.062136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Indexed: 06/04/2023]
Abstract
We ask what happens when two nonequilibrium systems in steady state are kept in contact and allowed to exchange a quantity, say mass, which is conserved in the combined system. Will the systems eventually evolve to a new stationary state where a certain intensive thermodynamic variable, like equilibrium chemical potential, equalizes following the zeroth law of thermodynamics and, if so, under what conditions is it possible? We argue that an equilibriumlike thermodynamic structure can be extended to nonequilibrium steady states having short-ranged spatial correlations, provided that the systems interact weakly to exchange mass with rates satisfying a balance condition-reminiscent of a detailed balance condition in equilibrium. The short-ranged correlations would lead to subsystem factorization on a coarse-grained level and the balance condition ensures both equalization of an intensive thermodynamic variable as well as ensemble equivalence, which are crucial for construction of a well-defined nonequilibrium thermodynamics. This proposition is proved and demonstrated in various conserved-mass transport processes having nonzero spatial correlations.
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Affiliation(s)
- Sayani Chatterjee
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700098, India
| | - Punyabrata Pradhan
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700098, India
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
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Kar IB, Singh AK, Mohapatra PC, Mohanty PK, Misra S. Repair of oral mucosal defects with cryopreserved human amniotic membrane grafts: prospective clinical study. Int J Oral Maxillofac Surg 2014; 43:1339-44. [PMID: 25132569 DOI: 10.1016/j.ijom.2014.07.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 06/19/2014] [Accepted: 07/23/2014] [Indexed: 12/11/2022]
Abstract
The aim of this study was to evaluate the clinical outcome of the surgical repair of oral mucosal defects using cryopreserved human amniotic membrane (HAM) as a graft material. Thirty-four patients with precancerous lesions such as leukoplakia, erythroplakia, and verrucous hyperplasia were included. Fresh amniotic membrane was obtained from women undergoing elective caesarean section; the membrane was cleaned, prepared in antibiotic solutions, and preserved at -80°C. Results suggested that HAM promotes healing and epithelialization without specific complications. Thus we conclude that the use of HAM gives promising results in the repair of post-surgical oral mucosal defects.
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Affiliation(s)
- I B Kar
- Department of Oral and Maxillofacial Surgery, SCB Dental College and Hospital, Cuttack, Odisha, India.
| | - A K Singh
- Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - P C Mohapatra
- Department of Biochemistry, SCB Medical College and Hospital, Cuttack, Odisha, India
| | - P K Mohanty
- Department of Dental Surgery, MKCG Medical College and Hospital, Berhampur, Odisha, India
| | - S Misra
- Department of Obstetrics and Gynaecology, SCB Medical College and Hospital, Cuttack, Odisha, India
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Chatterjee S, Pradhan P, Mohanty PK. Gammalike mass distributions and mass fluctuations in conserved-mass transport processes. Phys Rev Lett 2014; 112:030601. [PMID: 24484126 DOI: 10.1103/physrevlett.112.030601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Indexed: 06/03/2023]
Abstract
We show that, in conserved-mass transport processes, the steady-state distribution of mass in a subsystem is uniquely determined from the functional dependence of variance of the subsystem mass on its mean, provided that the joint mass distribution of subsystems is factorized in the thermodynamic limit. The factorization condition is not too restrictive as it would hold in systems with short-ranged spatial correlations. To demonstrate the result, we revisit a broad class of mass transport models and its generic variants, and show that the variance of the subsystem mass in these models is proportional to the square of its mean. This particular functional form of the variance constrains the subsystem mass distribution to be a gamma distribution irrespective of the dynamical rules.
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Affiliation(s)
- Sayani Chatterjee
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, India
| | - Punyabrata Pradhan
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, India
| | - P K Mohanty
- CMP Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India
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Basu M, Basu U, Bondyopadhyay S, Mohanty PK, Hinrichsen H. Fixed-energy sandpiles belong generically to directed percolation. Phys Rev Lett 2012; 109:015702. [PMID: 23031115 DOI: 10.1103/physrevlett.109.015702] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Indexed: 06/01/2023]
Abstract
Fixed-energy sandpiles with stochastic update rules are known to exhibit a nonequilibrium phase transition from an active phase into infinitely many absorbing states. Examples include the conserved Manna model, the conserved lattice gas, and the conserved threshold transfer process. It is believed that the transitions in these models belong to an autonomous universality class of nonequilibrium phase transitions, the so-called Manna class. Contrarily, the present numerical study of selected (1+1)-dimensional models in this class suggests that their critical behavior converges to directed percolation after very long time, questioning the existence of an independent Manna class.
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Affiliation(s)
- Mahashweta Basu
- TCMP Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India
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Mohanty PK, Dugad SR, Gupta SK. Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout. Rev Sci Instrum 2012; 83:043301. [PMID: 22559526 DOI: 10.1063/1.3698089] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A detailed description of a compact Monte Carlo simulation code "G3sim" for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.
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Affiliation(s)
- P K Mohanty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
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Abstract
We introduce a model of biological evolution in which species evolve in response to biotic interactions and fluctuating environmental stress. The species may either become extinct or mutate to acquire a new fitness value when the effective stress level is greater than their individual fitness. The model exhibits a phase transition to a completely extinct phase as the environmental stress or the mutation rate is varied. We discuss the generic conditions for which this transition is continuous. The model is exactly solvable and the critical behavior is characterized by an unusual dynamic exponent z=1/3. Apart from predicting large-scale evolution, the model can be applied to understand the trends in the available fossil data.
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Affiliation(s)
- Debarshee Bagchi
- Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India.
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Gupta S, Barma M, Basu U, Mohanty PK. Driven k-mers: correlations in space and time. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:041102. [PMID: 22181082 DOI: 10.1103/physreve.84.041102] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 08/14/2011] [Indexed: 05/31/2023]
Abstract
Steady-state properties of hard objects with exclusion interaction and a driven motion along a one-dimensional periodic lattice are investigated. The process is a generalization of the asymmetric simple exclusion process (ASEP) to particles of length k, and is called the k-ASEP. Here, we analyze both static and dynamic properties of the k-ASEP. Density correlations are found to display interesting features, such as pronounced oscillations in both space and time, as a consequence of the extended length of the particles. At long times, the density autocorrelation decays exponentially in time, except at a special k-dependent density when it decays as a power law. In the limit of large k at a finite density of occupied sites, the appropriately scaled system reduces to a nonequilibrium generalization of the Tonks gas describing the motion of hard rods along a continuous line. This allows us to obtain in a simple way the known two-particle distribution for the Tonks gas. For large but finite k, we also obtain the leading-order correction to the Tonks result.
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Affiliation(s)
- Shamik Gupta
- Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
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Basu U, Chaudhuri D, Mohanty PK. Bimodal response in periodically driven diffusive systems. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:031115. [PMID: 21517462 DOI: 10.1103/physreve.83.031115] [Citation(s) in RCA: 2] [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: 12/07/2010] [Indexed: 05/23/2023]
Abstract
We study the response of one-dimensional diffusive systems, consisting of particles interacting via symmetric or asymmetric exclusion, to time-periodic driving from two reservoirs coupled to the ends. The dynamical response of the system can be characterized in terms of the structure factor. We find an interesting frequency-dependent response; the current-carrying majority excitons cyclically crosses over from a short wavelength mode to a long wavelength mode with an intermediate regime of coexistence. This effect being boundary driven decays inversely with system size. Analytic calculations show that this behavior is common to diffusive systems, both in the absence and presence of correlations.
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Affiliation(s)
- Urna Basu
- TCMP Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India.
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Basu U, Mohanty PK. Totally asymmetric exclusion process on a ring with internal degrees of freedom. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 82:041117. [PMID: 21230248 DOI: 10.1103/physreve.82.041117] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Indexed: 05/30/2023]
Abstract
A totally asymmetric exclusion process on a ring with ν nonconserved internal degrees of freedom, where particles hop forward with a rate that depends on their internal state, has been studied. We show, using a mapping of the model to a zero range process with ν different kinds of boxes, that steady-state weights can be written in a matrix product form and calculate the spatial correlations exactly. A comparison of the model with an equivalent conserved system reveals that unequal hopping rates of particles belonging to different internal states are responsible for the nontrivial correlations.
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Affiliation(s)
- Urna Basu
- Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India.
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Abstract
Thermoinduction for 1 week, followed by 48 hours of vitamin treatment of seeds, resulted in complete annihilation of the cold effect, the plants from the treated seeds having shown a significant increase in elongation of the root and shoot and an increase in the fresh weight as well as in the dry matter over vernalized and unvernalized controls. An increase in vegetative vigor was also noted after treatment with vitamins at lower concentrations in the unvernalized series. Cold treatment not combined with vitamin treatment resulted in a decrease in vegetative vigor.
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Affiliation(s)
- J. R. Biswal
- Directorate of Research for Women in Agriculture, Indian Council of Agricultural Research (ICAR)
| | - P. K. Sahoo
- Directorate of Research for Women in Agriculture, Indian Council of Agricultural Research (ICAR)
| | - P. K. Mohanty
- Post Graduate Department of Zoology, Utkal University
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Basu U, Mohanty PK. Active-absorbing-state phase transition beyond directed percolation: a class of exactly solvable models. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:041143. [PMID: 19518209 DOI: 10.1103/physreve.79.041143] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Indexed: 05/27/2023]
Abstract
We introduce and solve a model of hardcore particles on a one-dimensional periodic lattice which undergoes an active-absorbing-state phase transition at finite density. In this model, an occupied site is defined to be active if its left neighbor is occupied and the right neighbor is vacant. Particles from such active sites hop stochastically to their right. We show that both the density of active sites and the survival probability vanish as the particle density is decreased below half. The critical exponents and spatial correlations of the model are calculated exactly using the matrix product ansatz. Exact analytical study of several variations of the model reveals that these nonequilibrium phase transitions belong to a new universality class different from the generic active-absorbing-state phase transition, namely, directed percolation.
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Affiliation(s)
- Urna Basu
- Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064, India.
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Mohanty PK, Jalan S. Analytical results for stochastically growing networks: connection to the zero-range process. Phys Rev E 2008; 77:045102. [PMID: 18517678 DOI: 10.1103/physreve.77.045102] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 02/08/2008] [Indexed: 11/07/2022]
Abstract
We introduce a stochastic model of growing networks where both the number of new nodes which join the network and the number of connections vary stochastically. We provide an exact mapping between this model and the zero-range process, and calculate analytically the degree distribution for any given evolution rule. We argue that this mapping can be used to infer a possible evolution rule for any given network. This is being demonstrated for a protein-protein interaction network of Saccharomyces cerevisiae.
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Affiliation(s)
- P K Mohanty
- TCMP Division, Saha Institute of Nuclear Physics, 1/AF, Saltlake, Kolkata 700064, India.
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Nonaka T, Hayashi Y, Ito N, Kawakami S, Matsuyama T, Oshima A, Tanaka H, Yoshikoshi T, Gupta SK, Jain A, Karthikeyan S, Mohanty PK, Morris SD, Rao BS, Ravindran KC, Sivaprasad K, Sreekantan BV, Tonwar SC, Viswanathan K, Kojima H. Did the 28 October 2003 solar flare accelerate protons to≳20 GeV? A study of the subsequent Forbush decrease with the GRAPES-3 tracking muon telescope. Int J Clin Exp Med 2006. [DOI: 10.1103/physrevd.74.052003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Mohanty PK. Generic features of the wealth distribution in ideal-gas-like markets. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 74:011117. [PMID: 16907070 DOI: 10.1103/physreve.74.011117] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Indexed: 05/11/2023]
Abstract
We provide an exact solution to the ideal-gas-like models studied in econophysics to understand the microscopic origin of Pareto law. In these classes of models the key ingredient necessary for having a self-organized scale-free steady-state distribution is the trading or collision rule where agents or particles save a definite fraction of their wealth or energy and invest the rest for trading. Using a Gibbs ensemble approach we could obtain the exact distribution of wealth in this model. Moreover we show that in this model (a) good savers are always rich and (b) every agent poor or rich invests the same amount for trading. Nonlinear trading rules could alter the generic scenario observed here.
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Affiliation(s)
- P K Mohanty
- Theoretical Condensed Matter Physics Division and Centre for Applied Mathematics and Computational Science, Saha Institute of Nuclear Physics, Kolkata, 700064 India.
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Padhi PK, Patel DK, Mohanty PK, Sahoo SC, Khan S. Factors predicting morbidity and mortality in idiopathic dilated cardiomyopathy--an inhospital survey. J Assoc Physicians India 2006; 54:587-8. [PMID: 17089913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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Kale SB, Reddy V, Mohanty PK, Patil R, Jariwala P. Absent Right Superior Vena Cava in Visceroatrial Situs Solitus : Surgical and Anaesthetic Implications. Ann Card Anaesth 2006. [DOI: 10.4103/0971-9784.37914] [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: 04/03/2023] Open
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Mohanty PK. First-order synchronization transition in locally coupled maps. Phys Rev E Stat Nonlin Soft Matter Phys 2004; 70:045202. [PMID: 15600449 DOI: 10.1103/physreve.70.045202] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2004] [Indexed: 05/24/2023]
Abstract
We study several diffusively coupled chaotic maps on periodic d -dimensional square lattices. Even and odd sublattices are updated alternately, introducing an effective delay. As the coupling strength is increased, the system undergoes a first-order phase transition from a multistable to a synchronized phase. At the transition point, the largest Lyapunov exponent of the system changes sign contrary to the earlier studies which predicted the same to be negative. Further increase in coupling strength shows desynchronization where the phase space splits into two ergodic regions. We argue that the nature of desynchronization transition strongly depends on the differentiability of the maps.
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Affiliation(s)
- P K Mohanty
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel 76100
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Abstract
We study sandpile models with stochastic toppling rules and having sticky grains so that with a nonzero probability no toppling occurs, even if the local height of pile exceeds the threshold value. Dissipation is introduced by adding a small probability of particle loss at each toppling. Generically for the models with a preferred direction, the avalanche exponents are those of critical directed percolation clusters. For undirected models, avalanche exponents are those of directed percolation clusters in one higher dimension.
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Affiliation(s)
- P K Mohanty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005, India
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Abstract
CONTEXT Active substance abuse is widely accepted as a contraindication for heart transplantation because of the theory that relapse would occur after transplantation and result in compromise of graft function, lowering long-term survival. Listing "recovering" substance abusers for heart transplantation has been controversial. OBJECTIVE To determine if substance abuse plays an unfavorable role in the outcome of heart transplantation. METHODS The medical records of all patients at our center who received a heart transplant more than 10 years ago were retrospectively reviewed for history of substance abuse. RESULTS From a pool of 189 transplant recipients, 47 patients had a definite history of substance abuse (group 1) and were considered in recovery, whereas 142 patients were clearly without any history of substance abuse (group 2). Group 1 had a significantly greater percentage of patients with a pretransplantation diagnosis of idiopathic cardiomyopathy (P = .003), a higher occurrence of heart-related cause of death (P = .017), and a significant prevalence of noncompliance (P = .0001) and death because of noncompliance (P = .0004). In contrast, group 2 surprisingly had a significantly higher incidence of death related to infection (P = .0062), which is unexplained. Despite higher incidence of noncompliance in group 1, there was no significant difference in the overall survival rate between the 2 groups. CONCLUSION These results suggest that patients with a history of substance abuse can undergo successful heart transplantation with acceptable long-term survival, though they are at greater risk for substance abuse relapse and resulting noncompliance with the treatment regimen. The extent to which relapse of substance abuse and its consequences affect the cost of posttransplantation care remains to be determined.
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Affiliation(s)
- J S Hanrahan
- McGuire Veterans Affairs Medical Center, Richmond, Va., USA
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Abstract
BACKGROUND AND OBJECTIVE Patients presenting with acute myocardial infarction who fail to respond to standard therapy with thrombolytics or have contraindications for their use oftentimes need revascularization with a mechanical device for removal of an occlusive coronary thrombus and its underlying atherosclerotic plaque. As both thrombi and plaques absorb laser energy in the ultraviolet wavelength (308 nm), we studied the feasibility and safety of excimer laser angioplasty in selective patients with complicated acute myocardial infarction. STUDY DESIGN/MATERIALS AND METHODS Fifty patients with acute myocardial infarction complicated by continuous chest pain and/or ischemia who had a total of 54 obstructive lesions were treated with percutaneous excimer coronary laser angioplasty (ELCA). A Q-wave myocardial infarction was documented in 56% and a non-Q-wave myocardial infarction in 44%. The baseline left ventricular ejection fraction was reduced at 43 +/- 13% and six patients (12%) presented to the cardiac catheterization laboratory in cardiogenic shock. Twenty-nine patients failed to respond to thrombolytic therapy and 16 had contraindications for thrombolytics and IIb/IIIa receptor antagonists. Following laser debulking, all patients received adjunct balloon dilation and then stents were deployed in 83% of the target lesions. Quantitative coronary arteriography (QCA) was performed at an independent core laboratory. RESULTS Ninety-eight percent laser success and 100% procedural success were achieved. By QCA the minimal luminal diameter increased from baseline of 0.7 +/- 0.5 to 1.3 +/- 0.5 mm post-lasing and then to 2.0 +/- 0.6 with balloon dilation to a final of 3.0 +/- 0.5 mm. Pre-laser percent stenosis diameter of 77 +/- 17% was reduced to 51 +/- 22% post-laser to 3.0 +/- 17% post-balloon and to a final of 15 +/- 25%. An 83% laser-induced reduction of thrombus burden area was achieved as well as an increase in TIMI flow from baseline of 1.7 +/- 1.1 to 2.8 +/- 0.4 by laser to a 2.9 +/- 0.4 final. There were no deaths, emergency bypass surgery, cerebral vascular accident, neurologic injury, or major perforation. In one case, a laser-induced major dissection was successfully treated by stenting. All 50 patients survived the procedure, improved clinically, and were discharged. CONCLUSION Application of excimer laser coronary angioplasty is feasible and safe in selected patients with acute myocardial infarction who either fail to respond to thrombolytics or have contraindications to these agents. Intracoronary thrombus at the target lesion can be successfully dissolved with this wavelength laser energy without adverse effect on the procedure results.
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Affiliation(s)
- O Topaz
- Division of Cardiology, McGuire VA Medical Center, Medical College of Virginia Hospitals, 1201 Broad Rock Road, Richmond, VA 23249, USA
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Davis FA, Mohanty PK, Burns DM, Andemichael YW. Sulfinimine-mediated asymmetric synthesis of 1,3-disubstituted tetrahydroisoquinolines: a stereoselective synthesis of cis- and trans-6,8-dimethoxy-1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline. Org Lett 2000; 2:3901-3. [PMID: 11101449 DOI: 10.1021/ol006654u] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [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: 11/29/2022]
Abstract
[reaction: see text] The highly diastereoselective addition of lateral lithiated o-tolunitriles to sulfinimines followed by treatment of the resulting sulfinamide with MeLi, hydrolysis, and reduction represents a concise new methodology for the asymmetric synthesis of 1,3-disubstituted tetrahydroisoquinolines.
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Affiliation(s)
- F A Davis
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA.
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Abstract
BACKGROUND AND OBJECTIVE Aggressive development of allograft coronary artery disease is a major cause of death in heart transplant recipients. Percutaneous balloon angioplasty is considered suboptimal for complex lesions in native coronary vessels and heart transplant recipients, alike. Excimer laser energy (308-nm wavelength) can successfully remove and vaporize atherosclerotic plaques in native coronary vessels; however, its application in heart transplant recipients has not been studied clinically yet. STUDY DESIGN/MATERIALS AND METHODS Six heart transplant recipients underwent percutaneous excimer laser (CVX-300, Spectranetics, Colorado Springs, CO) coronary angioplasty for treatment of a total of 10 discrete, obstructive coronary artery lesions. By using concentric or eccentric multifiber laser catheters, energy parameters were set at a fluence of 45 mJ/mm(2) or 60 mJ/mm(2) with a frequency of 25 Hz and 40 Hz, respectively, with a pulse duration of 135 ns and output of 200 mJ/pulse. The "saline flush" and "pulse and retreat" lasing techniques were used. In each case, adjunct balloon angioplasty was performed; in five lesions, an intracoronary stent was implanted. Angiographic evaluation was performed by visual assessment. RESULTS Each procedure was successful as defined by laser recanalization of the target lesion (reduction of target lesion stenosis in more than 20%) and subsequent adequate final luminal patency (reduction of target lesion stenosis to less than 50%) and absence of any major in-cardiac catheterization complication (such as perforation, acute closure, dissection, emergency coronary artery bypass surgery), or in-hospital complications (such as death, myocardial infarction, cardiac enzyme elevation, major bleeding), or need for surgical revascularization. A 92 +/- 5% preprocedural percent diameter stenosis was reduced by laser to 35 +/- 16% and by adjunct balloon angioplasty in all lesions and stenting in five lesions, to final residual stenosis of 2 +/- 6%. Angiographic follow-up between 2 and 6 months after the procedure demonstrated a target lesion restenosis rate of 22%. CONCLUSION Percutaneous excimer laser is safe and efficacious in the treatment of focal obstructive lesions caused by allograft coronary artery disease. These data represent an early clinical experience; thus, the long-term outcome of this revascularization method in recipients of heart transplantation will have to be determined by a large scale prospective, randomized, multicenter clinical study.
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Affiliation(s)
- O Topaz
- Interventional Cardiovascular Laboratories, McGuire VA Medical Center, Division of Cardiology, Medical College of Virginia/Virginia Commonwealth University, Richmond, Virginia 23249, USA
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Akosah KO, Denlinger B, Mohanty PK. Safety profile and hemodynamic responses to beta-adrenergic stimulation by dobutamine in heart transplant patients. Chest 1999; 116:1587-92. [PMID: 10593781 DOI: 10.1378/chest.116.6.1587] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVE Dobutamine stress echocardiography (DSE) has been used as a screening tool for coronary artery disease after heart transplantation and in the identification of patients at risk for development of cardiac events. However, the safety profile of high-dose dobutamine in heart transplant patients has not been systematically examined. Accordingly, we studied the safety profile and hemodynamic responses to escalating doses of dobutamine to determine the influence of denervation. DESIGN We assessed the hemodynamic responses, heart rate (HR), and arterial BP indexes (mean arterial pressure, systolic BP [SBP], diastolic BP [DBP], and pulse pressure) to dobutamine in 87 heart transplant patients ([mean +/- SD] age, 51 +/- 1 years) and compared the results with 97 nontransplant patients (age, 63.0 +/- 1 years) who served as innervated control subjects. MEASUREMENTS AND RESULTS The baseline HR (84 +/- 2 vs 69 +/- 1 beats/minute, respectively; p < 0.001) and peak HR response (144 +/- 2 vs 117 +/- 2 beats/minute, respectively; p < 0.001) were significantly higher in heart transplant patients than in the nontransplant patients. SBP was lower in heart transplant patients than in nontransplant patients at baseline (131 +/- 2 vs 138 +/- 2 mm Hg, respectively; p < 0.02) and at peak (150 +/- 3 vs 158 +/- 3 mm Hg, respectively; p < 0.03). However, baseline DBP was higher in transplant patients than in nontransplant patients (86 +/- 1 vs 77 +/- 1 mm Hg, respectively; p < 0.001). The decrease in DBP was similar in both groups (15 mm Hg). The dose-response curve for HR was shifted leftward in heart transplant patients. Heart transplant patients attained a higher absolute HR at each infusion stage and higher rates of increase, but the decrease in DBP was not significantly different in the two groups. CONCLUSIONS These results show that there is augmented chronotropic response and expected decline in DBP in response to dobutamine infusion in heart transplant patients. This increase in myocardial oxygen demand and a decrease in coronary perfusion pressure may be important mechanisms in the development of ischemic abnormalities that are detectable as regional dysynergy on echocardiography.
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Affiliation(s)
- K O Akosah
- Gundersen Lutheran Heart Institute, La Crosse, WI 54601, USA
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Rossignol DA, Kipreos B, Akosah K, Mohanty PK. Accelerated transplant coronary artery disease and massive silent acute myocardial infarction in a heart transplant patient--a case report and brief review of literature. Angiology 1999; 50:947-53. [PMID: 10580360 DOI: 10.1177/000331979905001110] [Citation(s) in RCA: 5] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This case report describes an aggressive form of accelerated atherosclerosis predicted early after transplant by dobutamine stress echocardiography in a patient who died of massive myocardial infarction 32 months after transplantation. The main objective finding of this event was markedly increased cardiac filling pressures during an elective cardiac catheterization and coronary angiography. The literature is briefly reviewed.
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Affiliation(s)
- D A Rossignol
- Division of Cardiology, Virginia Commonwealth University, Medical College of Virginia, McGuire VA Medical Center, Richmond 23249, USA
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Abstract
Accelerated allograft vasculopathy significantly limits the survival of heart transplant recipients. The prevalence of allograft coronary artery disease is as high as 18% by 1 year and 50% by 5 years following heart transplant. Heart failure and sudden cardiac death are the two most common clinical presentations. In heart transplant recipients with severe, discrete focal allograft vascular disease, percutaneous balloon angioplasty is a viable palliative option. However, its application is limited by a significant restenosis rate and progression of allograft disease in nontreated segments. Diffuse disease with tapering of vessels may be approached by debulking devices. Emerging revascularization modalities for focal stenoses and some of the diffuse tapering vessels include coronary stents, rotational atherectomy, various wavelength lasers, and, to a lesser extent, directional atherectomy. Conceivably, stents will reduce restenosis rates related to focal, discrete plaques; yet it is unknown whether they will be efficacious in short- and long-term treatment of diffusely diseased segments affected by allograft disease. Accurate assessment of clinical outcomes and long-term evaluation is imperative prior to acceptance of these devices as fundamental interventional tools for treatment of allograft coronary artery disease.
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Affiliation(s)
- O Topaz
- Cardiac Catheterization Laboratories, McGuire VA Medical Center and Medical College of Virginia Hospitals, Medical College of Virginia, Virginia Commonwealth University, Richmond 23249, USA
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Abstract
Bacterial endocarditis predominantly involves cardiac valves and is associated with many potential complications. Valvular dysfunction resulting from disruption of the structural integrity of valves are not infrequent. This report illustrates a rare case of endocarditis involving the interatrial septum which subsequently produced destruction of the structure resulting in an acquired atrial septal defect.
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Affiliation(s)
- A Prinz
- Division of Cardiology, Virginia Commonwealth University, Medical College of Virginia, McGuire Veterans Affairs Medical Center, Richmond 23249, USA
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Quigg R, Salyer J, Mohanty PK, Simpson P. Impaired exercise capacity late after cardiac transplantation: influence of chronotropic incompetence, hypertension, and calcium channel blockers. Am Heart J 1998; 136:465-73. [PMID: 9736138 DOI: 10.1016/s0002-8703(98)70221-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [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: 11/19/2022]
Abstract
BACKGROUND AND METHODS Patients undergoing orthotopic cardiac transplantation manifest reduced exercise capacity during the first postoperative year, which is related primarily to chronotropic incompetence of the denervated heart. To determine whether exercise capacity improves during the long term after transplantation, we prospectively studied 45 patients from 1 month to 6 years after cardiac transplantation by use of maximal treadmill exercise testing for measurement of exercise duration, peak heart rate, and peak VO2. All had normal left ventricular ejection fractions. Patients were categorized according to length of time since transplant and compared to 14 untrained normal subjects. RESULTS Peak exercise heart rate and exercise duration were progressively higher as time after transplantation increased. However, patients who had undergone transplantation more than 2 years earlier continued to manifest a significant reduction in peak exercise heart rate (157+/-3 beats/min vs 178+/-14 beats/min) and reduced exercise duration (8.6+/-0.5 minutes vs 13.2+/-2.0 minutes) compared with controls. In contrast, peak VO2 was similar at all times after transplant and remained markedly reduced in patients who underwent transplantation more than 2 years earlier as compared with controls (22.1+/-0.7 mL/kg/min vs 42.1+/-9.1 mL/kg/min). The potential effects of 14 clinical variables on exercise performance were evaluated by regression modeling. Patients with poorly controlled hypertension had a shorter median exercise duration (7.4 minutes vs 9.7 minutes) and a lower median peak VO2 (20.3 mL/kg/min vs 23.2 mL/kg/min) compared with patients with normal or well-controlled blood pressure. Patients treated with calcium channel blockers for hypertension had greater chronotropic incompetence during exercise (peak heart rate 139 beats/min vs 158 beats/min). There was no relation between exercise capacity and recipient age, donor age, recipient sex, donor ischemic time, pretransplant diagnosis, length of peritransplant hospitalization, percentage of ideal body weight, left ventricular ejection fraction, frequency or severity of allograft rejection, or long-term use of oral prednisone therapy. CONCLUSIONS Exercise capacity, as measured by treadmill exercise time and peak heart rate, improves in the first 2 years after transplantation, but does not reach normal values in patients up to 6 years after transplant. Peak VO2 remains significantly reduced at all times after transplantation despite the presence of normal resting left ventricular systolic function.
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Affiliation(s)
- R Quigg
- Division of Cardiology, Northwestern University, Chicago, Ill, USA
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Akosah KO, McDaniel S, Hanrahan JS, Mohanty PK. Dobutamine stress echocardiography early after heart transplantation predicts development of allograft coronary artery disease and outcome. J Am Coll Cardiol 1998; 31:1607-14. [PMID: 9626841 DOI: 10.1016/s0735-1097(98)00169-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES This study sought to determine the prognostic significance of serial dobutamine stress echocardiography (DSE) in new heart transplant recipients and to examine the relation between persistent wall motion abnormalities and the eventual development of coronary artery disease (CAD) as assessed by angiography. BACKGROUND Allograft CAD is a major cause of graft failure. However, clinical diagnosis of the early disease remains difficult. The reasons for this include the diffuse nature of the disease and its predilection for the microvasculature, which are not easily detected by coronary angiography. Identifying patients at risk for the development of angiographic CAD early after transplantation may allow such patients to be targeted for aggressive treatment options to prevent subsequent cardiac events and early graft failure. METHODS Twenty-two new heart transplant recipients were selected to undergo serial DSE at the time of their regularly scheduled endomyocardial biopsy. In addition, patients underwent scheduled annual coronary angiography. DSE was performed in 5-min stages with infusion of intravenous dobutamine at 5, 10, 20, 30 and 40 microg/kg body weight per min. RESULTS Twenty-two patients had 91 DSE studies and 45 coronary angiograms. The patients were categorized into three groups based on the echocardiographic results. Group 1 (n = 7) had normal serial stress echocardiographic studies. Group 2 (n = 4) had transient inducible wall motion abnormalities. Group 3 (n = 11) developed persistent wall motion abnormalities. During a mean follow-up time of 32 +/- 11 months (range 5 to 50), 8 (73%) of 11 patients in Group 3 developed events. The events included angiographic CAD (n = 7), myocardial infarction (MI) (n = 1) and cardiac death (n = 3). The patient who developed an MI had a normal coronary angiogram. No cardiac event or angiographic disease occurred in either Group 1 or 2 patients. CONCLUSIONS These results suggest that dobutamine-induced wall motion abnormalities, which are persistent in new heart transplant recipients, are predictive of the development of angiographic CAD, MI or death.
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Affiliation(s)
- K O Akosah
- Gunderson Lutheran Heart Institute, LaCrosse, Wisconsin 54601, USA.
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Topaz O, Bailey NT, Mohanty PK. Application of solid-state pulsed-wave, mid-infrared laser for percutaneous revascularization in heart transplant recipients. J Heart Lung Transplant 1998; 17:505-10. [PMID: 9628570] [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: 02/07/2023] Open
Abstract
BACKGROUND Severe allograft coronary artery disease is a significant cause of death in heart transplant recipients. Percutaneous revascularization has thus far been attempted with balloon angioplasty and, to a lesser extent, with directional atherectomy. The new, investigational, solid-state pulsed-wave mid-infrared laser (holmium:YAG) can vaporize and remove atheromatous and thrombotic plaques. This mechanism of plaque ablation may be useful for allograft coronary artery disease associated with focal stenoses deemed unsuitable for standard balloon angioplasty, especially thrombus-containing lesions. METHODS Five adult heart transplant recipients with severe focal stenoses related to allograft coronary artery disease underwent six laser angioplasty procedures. Laser catheters (2.1 microm, 250 to 600 mJ, 5 Hz) varying from 1.2 mm to 2.0 mm delivered 45 +/- 7.4 pulses (mean +/- SD). Five laser procedures were completed with adjunct balloon angioplasty and one with directional atherectomy. RESULTS Laser success (defined as stenosis reduction > 20%, no cardiac catheterization laboratory or in-hospital major complication) was achieved in six of seven lesions (85%), and the overall (laser and adjunct balloon) procedural success rate was 100%. No major complications occurred. Laser-assisted angioplasty reduced mean stenosis from 90% +/- 3% to 9% +/- 11%. All five patients recovered and were discharged. Angiographic follow-up demonstrated a 50% restenosis rate. CONCLUSIONS In selected heart transplant recipients laser-assisted angioplasty can provide safe and successful acute revascularization. Focal lesions considered "nonideal" for balloon angioplasty and, in particular, thrombotic lesions can benefit from application of this device; however, long-term reduction of restenosis rates is not expected from this modality.
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Affiliation(s)
- O Topaz
- Division of Cardiology, McGuire VA Medical Center, Medical College of Virginia, Virginia Commonwealth University, Richmond 23249, USA
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Abstract
The objective of this focused review is to describe the rationale, methods, and potential clinical applications of dobutamine stress echocardiography (DSE) in heart transplant recipients. More than 500 studies in 150 heart transplant patients who underwent this procedure (1991-96) are reviewed. Relevant studies from the medical literature that have assessed the utility of DSE in the diagnosis of transplant coronary artery disease (TCAD) are discussed, the predictive ability of DSE for development of TCAD is determined, and the prognostic value of this test in the heart transplant population is evaluated. The protocol of DSE used in the laboratory for this study is presented and discussed with reference to other major studies that have determined the sensitivity, specificity, and positive and negative predictive accuracies. Since many noninvasive cardiac tests have not been consistently optimal to detect TCAD, a substantial number of patients undergo routine surveillance with coronary angiography to define the presence and magnitude of TCAD. Recent studies with DSE have shown it to be valuable in the noninvasive diagnosis of TCAD and to have an accuracy unmatched by other widely used imaging modalities. Other important evolving indications for DSE in heart transplant patients, such as prediction of prognosis and occurrence of cardiac events, are briefly discussed. Based on this study and the currently available literature, DSE appears to be a highly reproducible noninvasive test which can be serially employed in the routine surveillance of coronary artery disease in heart transplant patients.
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Affiliation(s)
- K O Akosah
- McGuire VA Medical Center, Medical College of Virginia/Virginia Commonwealth University, Richmond 23249, USA
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Akosah KO, Olsovsky M, Kirchberg D, Salter D, Mohanty PK. Dobutamine stress echocardiography predicts cardiac events in heart transplant patients. Circulation 1996; 94:II283-8. [PMID: 8901761] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Cardiac transplantation is an accepted treatment modality for end-stage heart failure. Coronary artery disease remains a major cause of mortality in the long term after heart transplantation. Despite the high prevalence of coronary artery disease in heart transplant recipients, currently used noninvasive tests as well as invasive tests are highly unreliable in predicting prognosis. We sought to test the hypothesis that the abnormalities induced by dobutamine stress echocardiography (DSE) may be of prognostic value in predicting acute cardiac events and mortality in heart transplant patients. METHODS AND RESULTS We prospectively studied 86 survivors of orthotopic heart transplantation and followed them for a mean period of 2 years after the DSE. The patients' median age was 51 +/- 10 years, and mean duration since transplant was 57.7 +/- 29 months (range, 3 to 120 months, mean +/- SD). DSE was performed by a standard protocol (dobutamine 5, 10, 20, 30, and 40 micrograms.kg-1.min-1 at 5-minute stages). DSE was defined as positive for development of new or worsening regional wall motion abnormality or failure of augmentation. Nine patients were excluded from analysis (5 because of acute allograft rejection and 4 because of poor acoustic window). Thus, data from 77 patients were analyzed. Fifty-seven of 77 (74%) had positive DSE. After 24 months of follow-up, 19 of 57 patients with abnormal DSE (33%) experienced 22 major cardiac events. In contrast, no event occurred in patients with normal DSE. Of the 19 with cardiac events, there were 7 episodes of heart failure (including 3 deaths), 4 had unstable angina, and 5 died of cardiac causes. Three patients had myocardial infarction, and 3 others died of noncardiac causes. Among the variables examined, the baseline left ventricular ejection fraction was lower (44 +/- 3.8 versus 51 +/- 1.4) and peak wall motion score index was higher (2.01 +/- 0.4 versus 1.44 +/- 0.4) in the patients group with cardiac events than in those without events. CONCLUSIONS These results suggest that DSE has significant value in predicting prognosis in post-heart transplant patients. Further studies are needed to define the role of DSE as a routine test for predicting prognosis in cardiac transplant recipients.
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Affiliation(s)
- K O Akosah
- Department of Medicine, Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, VA 23249, USA
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50
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Bertolet BD, Anand IS, Bryg RJ, Mohanty PK, Chatterjee K, Cohn JN, Khurmi NS, Pepine CJ. Effects of A1 adenosine receptor agonism using N6-cyclohexyl-2'-O-methyladenosine in patients with left ventricular dysfunction. Circulation 1996; 94:1212-5. [PMID: 8822971 DOI: 10.1161/01.cir.94.6.1212] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND The role of adenosine as a neuromodulator in heart failure was studied with the use of a selective adenosine A1 receptor agonist, N6-cyclohexyl-2'-O-methyladenosine (SDZ-WAG 994). METHODS AND RESULTS Fifty patients with heart failure symptoms and moderate left ventricular systolic dysfunction had a balloon flotation catheter inserted. Patients received placebo or a single oral dose of either 1, 2, or 5 mg SDZ-WAG 994. After baseline measurements were obtained, hemodynamic and electrophysiological recordings were repeated at 30-minute intervals for the next 4 hours, then every 6 hours for the next 24 hours. Blood samples for norepinephrine, epinephrine, aldosterone, atrial natriuretic peptide, and plasma renin activity were drawn at baseline and 2 hours after drug administration. A adenosine receptor agonism produced no important effects on systemic, right atrial, pulmonary artery, or pulmonary capillary wedge pressures; cardiac index; respiratory rate; or heart rate. The PR interval (a reflection of A1 receptor-mediated activity) increased significantly in a stepwise fashion. At the 5-mg dose of SDZ-WAG 994, significant increases in atrial natriuretic peptide (216 +/- 137 to 407 +/- 146 pg/mL) and norepinephrine (477 +/- 243 to 618 +/- 237 pg/mL) levels were noted. CONCLUSIONS A1 adenosine receptor agonism with SDZ-WAG 994 resulted in no significant hemodynamic changes at rest in this subset of patients with left ventricular dysfunction. An increase in the PR interval and atrial natriuretic peptide level, consistent with adenosine A1 receptor-mediated activity, was observed. In addition, an increase in the norepinephrine level was observed, suggesting a role for adenosine as a peripheral nervous system neuromodulator.
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Affiliation(s)
- B D Bertolet
- Department of Medicine, University of Florida Health Sciences Center, Gainesville 32610-0277, USA
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