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Yaraghi N, Sharman R, Gopal R, Singh R, Ramesh R. Drivers of information disclosure on health information exchange platforms: insights from an exploratory empirical study. J Am Med Inform Assoc 2015; 22:1183-6. [PMID: 26275625 DOI: 10.1093/jamia/ocv086] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [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: 04/27/2015] [Accepted: 05/26/2015] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE The objective of this research is to empirically explore the drivers of patients' consent to sharing of their medical records on health information exchange (HIE) platforms. MATERIALS AND METHODS The authors analyze a dataset consisting of consent choices of 20,076 patients in Western New York. A logistic regression is applied to empirically investigate the effects of patients' age, gender, complexity of medical conditions, and the role of primary care physicians on patients' willingness to disclose medical information on HIE platforms. RESULTS The likelihood of providing consent increases by age (odds ratio (OR) = 1.055; P < .0001). Female patients are more likely to provide consent (OR = 1.460; P = .0003). As the number of different physicians involved in the care of the patient increases, the odds of providing consent slightly increases (OR = 1.024; P = .0031). The odds of providing consent is significantly higher for the patients whom a primary care physician has been involved in their medical care (OR = 1.323; P < .0001). CONCLUSION Individual-level characteristics are important predictors of patients' willingness to disclose their medical information on HIE platforms.
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Affiliation(s)
- Niam Yaraghi
- Center for Technology Innovation, Governance Studies, The Brookings Institution, Washington DC, 20036, USA
| | - Raj Sharman
- Department of Management Science and Systems, SUNY at Buffalo, Buffalo, New York 14260, USA
| | - Ram Gopal
- Department of Operations and Information Management, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Ranjit Singh
- Department of Management Science and Systems, SUNY at Buffalo, Buffalo, New York 14260, USA Department of Family Medicine, SUNY at Buffalo, Buffalo, New York, 14203, USA UB Patient Safety Research Center, State University of New York at Buffalo, Buffalo, New York 14203, USA
| | - R Ramesh
- Department of Management Science and Systems, SUNY at Buffalo, Buffalo, New York 14260, USA
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102
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Liu X, Dean MPM, Liu J, Chiuzbăian SG, Jaouen N, Nicolaou A, Yin WG, Rayan Serrao C, Ramesh R, Ding H, Hill JP. Probing single magnon excitations in Sr₂IrO₄ using O K-edge resonant inelastic x-ray scattering. J Phys Condens Matter 2015; 27:202202. [PMID: 25921058 DOI: 10.1088/0953-8984/27/20/202202] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Resonant inelastic x-ray scattering (RIXS) at the L-edge of transition metal elements is now commonly used to probe single magnon excitations. Here we show that single magnon excitations can also be measured with RIXS at the K-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin-orbit coupling. This is demonstrated with oxygen K-edge RIXS experiments on the perovskite Sr2IrO4, where low energy peaks from single magnon excitations were observed. This new application of RIXS has excellent potential to be applied to a wide range of magnetic systems based on heavy elements, for which the L-edge RIXS energy resolution in the hard x-ray region is usually poor.
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Affiliation(s)
- X Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA. Collaborative Innovation Center of Quantum Matter, Beijing, People's Republic of China
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103
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Mohamed Subarkhan M, Ramesh R. Binuclear ruthenium(III) bis(thiosemicarbazone) complexes: synthesis, spectral, electrochemical studies and catalytic oxidation of alcohol. Spectrochim Acta A Mol Biomol Spectrosc 2015; 138:264-270. [PMID: 25498823 DOI: 10.1016/j.saa.2014.11.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [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: 09/10/2014] [Revised: 11/03/2014] [Accepted: 11/20/2014] [Indexed: 06/04/2023]
Abstract
A new series of binuclear ruthenium(III) thiosemicarbazone complexes of general formula [(EPh3)2(X)2Ru-L-Ru(X)2(EPh3)2] (where E=P or As; X=Cl or Br; L=NS chelating bis(thiosemicarbazone ligands) has been synthesized and characterized by analytical and spectral (FT-IR, UV-Vis and EPR). IR spectra show that the thiosemicarbazones behave as monoanionic bidentate ligands coordinating through the azomethine nitrogen and thiolate sulphur. The electronic spectra of the complexes indicate that the presence of d-d and intense LMCT transitions in the visible region. The complexes are paramagnetic (low spin d(5)) in nature and all the complexes show rhombic distortion around the ruthenium ion with three different 'g' values (gx≠gy≠gz) at 77K. All the complexes are redox active and exhibit an irreversible metal centered redox processes (Ru(III)-Ru(III)/Ru(IV)-Ru(IV); Ru(III)-Ru(III)/Ru(II)-Ru(II)) within the potential range of 0.38-0.86V and -0.39 to -0.66 V respectively, versus Ag/AgCl. Further, the catalytic efficiency of one of the complexes [Ru2Cl2(AsPh3)4(L1)] (4) has been investigated in the case of oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide(NMO) as co-oxidant. The formation of high valent Ru(V)O species is proposed as catalytic intermediate for the catalytic cycle.
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Affiliation(s)
- M Mohamed Subarkhan
- School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India
| | - R Ramesh
- School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
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104
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Achari GA, Ramesh R. Characterization of bacteria degrading 3-hydroxy palmitic acid methyl ester (3OH-PAME), a quorum sensing molecule of Ralstonia solanacearum. Lett Appl Microbiol 2015; 60:447-55. [PMID: 25580768 DOI: 10.1111/lam.12389] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [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: 08/04/2014] [Revised: 01/05/2015] [Accepted: 01/05/2015] [Indexed: 11/29/2022]
Abstract
UNLABELLED Bacterial wilt pathogen Ralstonia solanacearum causes severe crop loss of eggplant, which is of economic importance in India. 3-hydroxy palmitic acid methyl ester (3OH-PAME) is the main quorum sensing molecule governing the expression of virulence factors in R. solanacearum. Ability of 164 bacterial isolates from the xylem of eggplant (Solanum melongena L.), chilli pepper (Capsicum annuum L.) and wild eggplant (Solanum torvum Sw.) to degrade 3OH-PAME was tested by disc diffusion assay. Enzymatic degradation of 3OH-PAME by five bacteria was confirmed by High-Performance Liquid Chromatography-Mass Spectrometry analysis. 3OH-PAME degrading bacteria were identified as Stenotrophomonas maltophilia, Pseudomonas aeruginosa and Rhodococcus corynebacterioides. 3OH-PAME degrading bacteria reduced the expression of virulence factors (exopolysaccharides and endoglucanase) of R. solanacearum in vitro and reduced wilt incidence in eggplant seedlings under greenhouse conditions. Isolates with quorum quenching activity successfully re-colonized eggplant seedlings. Quorum quenching bacteria produced antagonistic compounds, which may act synergistically with quorum quenching in reducing bacterial wilt in eggplant. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first report on endophytic bacteria of class Gammaproteobacteria and phylum Actinobacteria having 3OH-PAME degrading activity. This study demonstrates the potential use of endophytic bacteria as quorum quenching biocontrol agents for management of bacterial wilt in eggplant.
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Affiliation(s)
- G A Achari
- ICAR Research Complex for Goa, Old Goa, Goa, India; Department of Microbiology, Goa University, Taleigao Plateau, Goa, India
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105
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Lee Y, Liu ZQ, Heron JT, Clarkson JD, Hong J, Ko C, Biegalski MD, Aschauer U, Hsu SL, Nowakowski ME, Wu J, Christen HM, Salahuddin S, Bokor JB, Spaldin NA, Schlom DG, Ramesh R. Large resistivity modulation in mixed-phase metallic systems. Nat Commun 2015; 6:5959. [DOI: 10.1038/ncomms6959] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/26/2014] [Indexed: 11/09/2022] Open
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106
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Fina I, Marti X, Yi D, Liu J, Chu JH, Rayan-Serrao C, Suresha S, Shick AB, Zelezný J, Jungwirth T, Fontcuberta J, Ramesh R. Anisotropic magnetoresistance in an antiferromagnetic semiconductor. Nat Commun 2014; 5:4671. [PMID: 25204755 DOI: 10.1038/ncomms5671] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 07/11/2014] [Indexed: 11/09/2022] Open
Abstract
Recent studies in devices comprising metal antiferromagnets have demonstrated the feasibility of a novel spintronic concept in which spin-dependent phenomena are governed by an antiferromagnet instead of a ferromagnet. Here we report experimental observation of the anisotropic magnetoresistance in an antiferromagnetic semiconductor Sr2IrO4. Based on ab initio calculations, we associate the origin of the phenomenon with large anisotropies in the relativistic electronic structure. The antiferromagnet film is exchange coupled to a ferromagnet, which allows us to reorient the antiferromagnet spin-axis in applied magnetic fields via the exchange spring effect. We demonstrate that the semiconducting nature of our AFM electrode allows us to perform anisotropic magnetoresistance measurements in the current-perpendicular-to-plane geometry without introducing a tunnel barrier into the stack. Temperature-dependent measurements of the resistance and anisotropic magnetoresistance highlight the large, entangled tunabilities of the ordinary charge and spin-dependent transport in a spintronic device utilizing the antiferromagnet semiconductor.
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Affiliation(s)
- I Fina
- 1] Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, E-08193 Barcelona, Spain [2] Experimental Department II, Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany
| | - X Marti
- 1] Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA [2] Centre d'Investigació en Nanociència i Nanotecnologia (CIN2), CSIC-ICN, 08193 Barcelona, Spain [3] Department of Spintronics and Nanoelectronics, Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - D Yi
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - J Liu
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - J H Chu
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - C Rayan-Serrao
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - S Suresha
- National Center for Electron Microscopy, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - A B Shick
- Department of Condensed Matter Theory, Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - J Zelezný
- Department of Spintronics and Nanoelectronics, Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - T Jungwirth
- 1] Department of Spintronics and Nanoelectronics, Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic [2] School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - J Fontcuberta
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, E-08193 Barcelona, Spain
| | - R Ramesh
- 1] Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA [2] Department of Physics, University of California, Berkeley, California 94720, USA [3] National Center for Electron Microscopy, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [4]
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107
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Singh S, Haraldsen JT, Xiong J, Choi EM, Lu P, Yi D, Wen XD, Liu J, Wang H, Bi Z, Yu P, Fitzsimmons MR, MacManus-Driscoll JL, Ramesh R, Balatsky AV, Zhu JX, Jia QX. Induced magnetization in La0.7Sr0.3MnO3/BiFeO3 superlattices. Phys Rev Lett 2014; 113:047204. [PMID: 25105651 DOI: 10.1103/physrevlett.113.047204] [Citation(s) in RCA: 5] [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: 07/18/2013] [Indexed: 06/03/2023]
Abstract
Using polarized neutron reflectometry, we observe an induced magnetization of 75 ± 25 kA/m at 10 K in a La(0.7)Sr(0.3)MnO(3) (LSMO)/BiFeO(3) superlattice extending from the interface through several atomic layers of the BiFeO(3) (BFO). The induced magnetization in BFO is explained by density functional theory, where the size of band gap of BFO plays an important role. Considering a classical exchange field between the LSMO and BFO layers, we further show that magnetization is expected to extend throughout the BFO, which provides a theoretical explanation for the results of the neutron scattering experiment.
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Affiliation(s)
- Surendra Singh
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085, India
| | - J T Haraldsen
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Department of Physics and Astronomy, James Madison University, Harrisonburg, Virginia 22807, USA
| | - J Xiong
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and State Key Lab of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610051, China
| | - E M Choi
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom
| | - P Lu
- Sandia National Laboratory, Albuquerque, New Mexico 87185, USA
| | - D Yi
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - X-D Wen
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Liu
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - H Wang
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - Z Bi
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P Yu
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - M R Fitzsimmons
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J L MacManus-Driscoll
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom
| | - R Ramesh
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - A V Balatsky
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Jian-Xin Zhu
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Q X Jia
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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108
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Niranjan G, Anitha D, Srinivasan AR, Velu VK, Venkatesh C, Babu MS, Ramesh R, Saha S. Association of inflammatory sialoproteins, lipid peroxides and serum magnesium levels with cardiometabolic risk factors in obese children of South Indian population. Int J Biomed Sci 2014; 10:118-23. [PMID: 25018680 PMCID: PMC4092079] [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] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/20/2014] [Indexed: 06/03/2023]
Abstract
The Incidence of childhood obesity and metabolic syndrome is increasing even in rural and semi-urban regions of India. Adipose tissue mass secretes several inflammatory proteins, which could potentially alter the metabolic processes, leading to several complications at the later stages of life. With limited studies on protein bound sialic acid (PBSA) as a marker of oxidative stress mediated inflammation in obese children, this study was aimed to assess and correlate PBSA with lipid peroxidation and other cardiometabolic risk factors like Insulin Resistance (IR), serum magnesium, and high sensitive C reactive Protein (hsCRP) levels in order to provide an insight into the degree of systemic inflammation and oxidative stress. This study included 62 obese children (≥95% percentile of the CDC chart) and 60 non obese controls. This study documents significant higher levels of PBSA, IR, Malondialdehyde (MDA), hsCRP and uric acid in obese children (p<0.001). PBSA was associated with IR, hsCRP, uric acid, hypomagnesaemia. Higher degrees of oxidative stress, Insulin resistance and low serum magnesium levels were noted in obese children. PBSA and hsCRP levels were elevated and were associated with Insulin resistance in obese children of South Indian population.
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Affiliation(s)
- G. Niranjan
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
| | - D. Anitha
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
| | - A. R. Srinivasan
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
| | - V. Kuzhandai Velu
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
| | - C. Venkatesh
- Department of Pediatrics, JIPMER, Puducherry-605006, India
| | - M. Sathish Babu
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
| | - R. Ramesh
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
| | - S. Saha
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth [SBV], Pillaiyarkuppam, Puducherry-607402, India
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109
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Sathiya R, Velu VK, Niranjan G, Srinivasan AR, Amirtha GB, Ramesh R, Babu MS, Saha S. A Comparative Study of Serum Uric Acid levels and Lipid Ratios in Coronary Artery Disease Patients. Int J Biomed Sci 2014; 10:124-8. [PMID: 25018681 PMCID: PMC4092080] [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] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/06/2014] [Indexed: 11/11/2022]
Abstract
INTRODUCTION Coronary Artery Disease (CAD) appears to be common in the Indian population of different geographical origins, religions and languages. Measurement of lipid fractions and ratios are widely recommended for risk assessment. A few studies have shown that serum uric acid plays a role in the development of cardiovascular morbidity. Very few reports are cited linking serum uric acid with the lipid fraction in CAD. OBJECTIVES To find the significance of non-HDL cholesterol, LDL-c/HDL-c ratio, TC/HDL ratio and serum uric acid level in CAD patients. SUBJECTS AND METHODOLOGY In this study, we included fifty CAD patients as subjects and an equal number of controls. Both subjects and controls were assessed for anthropometric, physiological and biochemical parameters. RESULTS The present study showed significant increased levels of total cholesterol (p=0.002), TAGs (p<0.001), HDL (p=0.005), LDL (p<0.006) and non-HDL cholesterol (p<0.001). LDL-c/HDL-c ratio (p<0.001) and TC/HDL ratio (p<0.001) in CAD patients (subjects) were also significant when compared to controls. Uric acid level in CAD patients was increased (p<0.001). CONCLUSION Serum Uric Acid, TC/HDL and LDL/HDL ratios could be regarded as objective markers, in association with existing atherogenic dyslipidemia in patients with CAD.
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Affiliation(s)
- R. Sathiya
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - V. Kuzhandai Velu
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - G. Niranjan
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - A. R. Srinivasan
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - Ganesh B. Amirtha
- Department of Cardiology, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - R. Ramesh
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - M. Sathish Babu
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
| | - Subiman Saha
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute (SBV), Pillaiyarkuppam, Puducherry, India
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110
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Marti X, Fina I, Frontera C, Liu J, Wadley P, He Q, Paull RJ, Clarkson JD, Kudrnovský J, Turek I, Kuneš J, Yi D, Chu JH, Nelson CT, You L, Arenholz E, Salahuddin S, Fontcuberta J, Jungwirth T, Ramesh R. Room-temperature antiferromagnetic memory resistor. Nat Mater 2014; 13:367-374. [PMID: 24464243 DOI: 10.1038/nmat3861] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 12/10/2013] [Indexed: 06/03/2023]
Abstract
The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.
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Affiliation(s)
- X Marti
- 1] Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA [2] Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 12116 Praha 2, Czech Republic [3] Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - I Fina
- 1] Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain [2] Max Planck Institute of Microstructure Physics, Weinberg 2, Halle D-06120, Germany
| | - C Frontera
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain
| | - Jian Liu
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - P Wadley
- 1] Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic [2] School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Q He
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - R J Paull
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA
| | - J D Clarkson
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA
| | - J Kudrnovský
- Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - I Turek
- 1] Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 12116 Praha 2, Czech Republic [2] Institute of Physics of Materials ASCR, v.v.i., Zizkova 22, Brno 616 62, Czech Republic
| | - J Kuneš
- Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - D Yi
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J-H Chu
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C T Nelson
- National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - L You
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S Salahuddin
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720, USA
| | - J Fontcuberta
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain
| | - T Jungwirth
- 1] Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic [2] School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - R Ramesh
- 1] Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA [2] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Abstract
Since the re-emergence of multi-ferroics and magnetoelectrics almost a decade ago, bismuth ferrite has been among the most heavily studied model system. It is a multi-ferroic with robust ferroelectricity and antiferromagnetism, in conjunction with weak ferromagnetism arising primarily from spin-orbit coupling effects. This material system has generated a significant amount of discussion in the community, because many of the physical properties measured in thin films are different from the bulk. This paper summarizes some of the key observations in this versatile materials system, with a particular focus on thin films, heterostructures and interfacial phenomena.
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Affiliation(s)
- R Ramesh
- Departments of Materials Science and Engineering and Physics, University of California, , Berkeley, CA 94720, USA
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Kanchana Devi A, Ramesh R. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand. Spectrochim Acta A Mol Biomol Spectrosc 2014; 117:138-143. [PMID: 23988528 DOI: 10.1016/j.saa.2013.07.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [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: 04/23/2013] [Revised: 07/04/2013] [Accepted: 07/21/2013] [Indexed: 06/02/2023]
Abstract
Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E=P or As; X=Cl or Br; L=binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx≠gy≠gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (Ru(III)-Ru(III)/Ru(III)-Ru(IV); Ru(III)-Ru(IV)/Ru(IV)-Ru(IV)) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.
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Affiliation(s)
- A Kanchana Devi
- School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, India
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113
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Hariharan G, Purvaja R, Ramesh R. Toxic effects of lead on biochemical and histological alterations in green mussel (Perna viridis) induced by environmentally relevant concentrations. J Toxicol Environ Health A 2014; 77:246-260. [PMID: 24588225 DOI: 10.1080/15287394.2013.861777] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Acute and chronic toxicity tests were conducted on green mussel (Perna viridis) to determine the adverse effects of lead (Pb). Exposure of organisms to acute toxicity test for 96 h and lethal concentration (LC(50)) was the endpoint of the test. Acute toxicity for 96-h LC(50) and 95% confidence intervals of P. viridis was 2.62 ± 0.12 (2.62-3.24) mg/L Pb. Chronic toxicity tests revealed that survival of exposed organisms decreased with elevated exposure concentrations. No-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC) were calculated based on survival of test organisms. Results of this study demonstrated an increase in toxicity in test organisms with rise in exposure time and concentration. In this study, histology and biochemical enzymes, namely, catalase, reduced glutathione, glutathione S-transferase, and lipid peroxides, were correlated with chronic value and survival endpoints of P. viridis after chronic exposure to Pb. Biochemical and histological responses to different concentrations of Pb were assessed and significant differences were observed between control and increasing exposure concentrations. Biomarker studies in internal organs confirmed that the observed changes are due to adverse effects of Pb. This assessment of toxicity was the first step to determining the seawater quality criteria for marine organisms.
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Affiliation(s)
- G Hariharan
- a Institute for Ocean Management , Anna University Chennai , Chennai , Tamil Nadu , India
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114
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Murugan R, Ramesh R, Padmanabhan K. Investigation on Static and Dynamic Mechanical Properties of Epoxy Based Woven Fabric Glass/Carbon Hybrid Composite Laminates. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.proeng.2014.12.270] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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115
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Jyothirmai S, Ramesh R, Swarnalatha T, Renuka D. A Finite Element Approach to Bending, Contact and Fatigue Stress Distribution in Helical Gear Systems. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.mspro.2014.07.159] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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116
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Ramesh R, Loganathan R, Menon SS, Baskar K, Singh S. Controlled nucleation and growth of nanostructures by employing surface modified GaN based layers/heterostructures as bottom layer. RSC Adv 2014. [DOI: 10.1039/c3ra45250f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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117
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Yaraghi N, Du AY, Sharman R, Gopal RD, Ramesh R, Singh R, Singh G. Professional and geographical network effects on healthcare information exchange growth: does proximity really matter? J Am Med Inform Assoc 2013; 21:671-8. [PMID: 24287171 DOI: 10.1136/amiajnl-2012-001293] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND AND OBJECTIVE We postulate that professional proximity due to common patients and geographical proximity among practice locations are significant factors influencing the adoption of health information exchange (HIE) services by healthcare providers. The objective of this study is to investigate the direct and indirect network effects of these drivers on HIE diffusion. DESIGN Multi-dimensional scaling and clustering are first used to create different clusters of physicians based on their professional and geographical proximities. Extending the Bass diffusion model to capture direct and indirect network effects among groups, the growth of HIE among these clusters is modeled and studied. The network effects among the clusters are investigated using adoption data over a 3-year period for an HIE based in Western New York. MEASUREMENT HIE adoption parameters-external sources of influence as well as direct and indirect network coefficients-are estimated by the extended version of the Bass diffusion model. RESULTS Direct network effects caused by common patients among physicians are much more influential on HIE adoption as compared with previously investigated social contagion and external factors. Professional proximity due to common patients does influence adoption decisions; geographical proximity is also influential, but its effect is more on rural than urban physicians. CONCLUSIONS Flow of patients among different groups of physicians is a powerful factor in HIE adoption. Rather than merely following the market trend, physicians appear to be influenced by other physicians with whom they interact with and have common patients.
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Affiliation(s)
- Niam Yaraghi
- Department of Management Science and Systems, School of Management, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Anna Ye Du
- Department of Management Science and Systems, School of Management, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Raj Sharman
- Department of Management Science and Systems, School of Management, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Ram D Gopal
- Department of Management Science and Systems, School of Management, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - R Ramesh
- School of Business, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Ranjit Singh
- Department of Family Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA UB Patient Safety Research Center, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Gurdev Singh
- Department of Family Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA UB Patient Safety Research Center, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
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118
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Yi D, Liu J, Okamoto S, Jagannatha S, Chen YC, Yu P, Chu YH, Arenholz E, Ramesh R. Tuning the competition between ferromagnetism and antiferromagnetism in a half-doped manganite through magnetoelectric coupling. Phys Rev Lett 2013; 111:127601. [PMID: 24093300 DOI: 10.1103/physrevlett.111.127601] [Citation(s) in RCA: 6] [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: 03/27/2013] [Revised: 07/22/2013] [Indexed: 06/02/2023]
Abstract
We investigate the possibility of controlling the magnetic phase transition of the heterointerface between a half-doped manganite La(0.5)Ca(0.5)MnO(3) and a multiferroic BiFeO(3) (BFO) through magnetoelectric coupling. Using macroscopic magnetometry and element-selective x-ray magnetic circular dichroism at the Mn and Fe L edges, we discover that the ferroelectric polarization of BFO controls simultaneously the magnetization of BFO and La(0.5)Ca(0.5)MnO(3) (LCMO). X-ray absorption spectra at the oxygen K edge and linear dichroism at the Mn L edge suggest that the interfacial coupling is mainly derived from the superexchange between Mn and Fe t(2g) spins. The combination of x-ray absorption spectroscopy and mean-field theory calculations reveals that the d-electron modulation of Mn cations changes the magnetic coupling in LCMO, which controls the enhanced canted moments of interfacial BFO via the interfacial coupling. Our results demonstrate that the competition between ferromagnetic and antiferromagnetic instability can be modulated by an electric field at the heterointerface, providing another pathway for the electrical field control of magnetism.
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Affiliation(s)
- Di Yi
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA
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119
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Huijben M, Yu P, Martin LW, Molegraaf HJA, Chu YH, Holcomb MB, Balke N, Rijnders G, Ramesh R. Ultrathin limit of exchange bias coupling at oxide multiferroic/ferromagnetic interfaces. Adv Mater 2013; 25:4739-4745. [PMID: 23847010 DOI: 10.1002/adma.201300940] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 05/13/2013] [Indexed: 06/02/2023]
Abstract
Exchange bias coupling at the multiferroic- ferromagnetic interface in BiFeO₃ /La₀.₇ Sr₀.₃ MnO₃ heterostructures exhibits a critical thickness for ultrathin BiFeO₃ layers of 5 unit cells (2 nm). Linear dichroism measurements demonstrate the dependence on the BiFeO₃ layer thickness with a strong reduction for ultrathin layers, indicating diminished antiferromagnetic ordering that prevents interfacial exchange bias coupling.
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Affiliation(s)
- M Huijben
- MESA+ Institute for Nanotechnology, University of Twente, P.O. BOX 217, 7500 AE, Enschede, The Netherlands.
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120
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Lubk A, Rossell MD, Seidel J, Chu YH, Ramesh R, Hÿtch MJ, Snoeck E. Electromechanical coupling among edge dislocations, domain walls, and nanodomains in BiFeO3 revealed by unit-cell-wise strain and polarization maps. Nano Lett 2013; 13:1410-1415. [PMID: 23418908 DOI: 10.1021/nl304229k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The performance of ferroelectric devices, for example, the ferroelectric field effect transistor, is reduced by the presence of crystal defects such as edge dislocations. For example, it is well-known that edge dislocations play a crucial role in the formation of ferroelectric dead-layers at interfaces and hence finite size effects in ferroelectric thin films. The detailed lattice structure including the relevant electromechanical coupling mechanisms in close vicinity of the edge dislocations is, however, not well-understood, which hampers device optimization. Here, we investigate edge dislocations in ferroelectric BiFeO3 by means of spherical aberration-corrected scanning transmission electron microscopy, a dedicated model-based structure analysis, and phase field simulations. Unit-cell-wise resolved strain and polarization profiles around edge dislocation reveal a wealth of material states including polymorph nanodomains and multiple domain walls characteristically pinned to the dislocation. We locally determine the piezoelectric tensor and identify piezoelectric coupling as the driving force for the observed phenomena, explaining, for example, the orientation of the domain wall with respect to the edge dislocation. Furthermore, an atomic model for the dislocation core is derived.
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Affiliation(s)
- A Lubk
- Triebenberg Laboratory, Institute of Structure Physics, Technische Universität Dresden, 01062 Dresden, Germany.
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121
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Abstract
The importance of the Healthcare Information Exchange (HIE) in increasing healthcare quality and reducing risks and costs has led to greater interest in identifying factors that enhance adoption and meaningful use of HIE by healthcare providers. In this research we study the interlinked network effects between two different groups of physicians -- primary care physicians and specialists -- as significant factors in increasing the growth of each group in an exchange. An analytical model of interlinked and intragroup influences on adoption is developed using the Bass diffusion model as a basis. Adoption data on 1,060 different primary and secondary care physicians over 32 consecutive months was used to test the model. The results indicate not only the presence of interlinked effects, but also that their influence is stronger than that of the intragroup. Further, the influence of primary care physicians on specialists is stronger than that of specialists on primary care physicians. We also provide statistical evidence that the new model performs better than the conventional Bass model, and the assumptions of diffusion symmetry in the market are statistically valid. Together, the findings provide important guidelines on triggers that enhance the overall growth of HIE and potential marketing strategies for HIE services.
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Affiliation(s)
| | | | | | | | - R. Ramesh
- State University of New York at Buffalo
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122
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Abstract
We report the creation of a multiferroic field effect device with a BiFeO(3) (BFO) (antiferromagnetic-ferroelectric) gate dielectric and a La(0.7)Sr(0.3)MnO(3) (LSMO) (ferromagnetic) conducting channel that exhibits direct, bipolar electrical control of exchange bias. We show that exchange bias is reversibly switched between two stable states with opposite exchange bias polarities upon ferroelectric poling of the BFO. No field cooling, temperature cycling, or additional applied magnetic or electric field beyond the initial BFO polarization is needed for this bipolar modulation effect. Based on these results and the current understanding of exchange bias, we propose a model to explain the control of exchange bias. In this model the coupled antiferromagnetic-ferroelectric order in BFO along with the modulation of interfacial exchange interactions due to ionic displacement of Fe(3+) in BFO relative to Mn(3+/4+) in LSMO cause bipolar modulation.
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Affiliation(s)
- S M Wu
- Department of Physics, University of California, Berkeley, California 94720, USA.
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123
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von Glasow R, Jickells TD, Baklanov A, Carmichael GR, Church TM, Gallardo L, Hughes C, Kanakidou M, Liss PS, Mee L, Raine R, Ramachandran P, Ramesh R, Sundseth K, Tsunogai U, Uematsu M, Zhu T. Megacities and large urban agglomerations in the coastal zone: interactions between atmosphere, land, and marine ecosystems. Ambio 2013; 42:13-28. [PMID: 23076973 PMCID: PMC3547459 DOI: 10.1007/s13280-012-0343-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [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: 01/23/2012] [Revised: 06/29/2012] [Accepted: 08/16/2012] [Indexed: 05/25/2023]
Abstract
Megacities are not only important drivers for socio-economic development but also sources of environmental challenges. Many megacities and large urban agglomerations are located in the coastal zone where land, atmosphere, and ocean meet, posing multiple environmental challenges which we consider here. The atmospheric flow around megacities is complicated by urban heat island effects and topographic flows and sea breezes and influences air pollution and human health. The outflow of polluted air over the ocean perturbs biogeochemical processes. Contaminant inputs can damage downstream coastal zone ecosystem function and resources including fisheries, induce harmful algal blooms and feedback to the atmosphere via marine emissions. The scale of influence of megacities in the coastal zone is hundreds to thousands of kilometers in the atmosphere and tens to hundreds of kilometers in the ocean. We list research needs to further our understanding of coastal megacities with the ultimate aim to improve their environmental management.
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Affiliation(s)
- Roland von Glasow
- />School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ UK
| | - Tim D. Jickells
- />School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ UK
| | | | - Gregory R. Carmichael
- />Department of Chemical & Biochemical Engineering, The University of Iowa, Iowa City, IA 52242 USA
| | - Tom M. Church
- />School of Marine Science and Policy, University of Delaware, Newark, DE 19716-3501 USA
| | - Laura Gallardo
- />Departamento de Geofísica & Centro de Modelamiento Matemático, Universidad de Chile, Blanco Encalada 2002, Piso 4, Santiago, Chile
| | - Claire Hughes
- />Environment Department, University of York, Heslington, York, YO10 5DD UK
| | - Maria Kanakidou
- />Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, P.O. Box 2208, 71003 Heraklion, Greece
| | - Peter S. Liss
- />School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ UK
| | - Laurence Mee
- />Scottish Marine Institute, Scottish Association for Marine Science (SAMS), Oban, Argyll, PA37 1QA UK
| | - Robin Raine
- />The Ryan Institute for Environmental, Marine and Energy Research, National University of Ireland, Galway, Ireland
| | | | - R. Ramesh
- />Institute for Ocean Management, Anna University, Chennai, 600 025 India
| | - Kyrre Sundseth
- />Center for Ecology and Economics (CEE), NILU-Norwegian Institute for Air Research, Instituttveien 18, P.O. Box 100, 2007 Kjeller, Norway
| | - Urumu Tsunogai
- />Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 Japan
| | - Mitsuo Uematsu
- />Center for International Collaboration, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564 Japan
| | - Tong Zhu
- />State Key Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871 China
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124
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Niranjan G, Mohanavalli V, Srinivasan AR, Ramesh R. Serum lipid peroxides and magnesium levels following three months of treatment with pioglitazone in patients with type-2 diabetes mellitus. Diabetes Metab Syndr 2013; 7:35-37. [PMID: 23517794 DOI: 10.1016/j.dsx.2013.02.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [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: 12/11/2022]
Abstract
BACKGROUND Higher levels of lipid peroxidation and hypomagnesaemia are frequently associated with Type 2 Diabetes mellitus (T2DM). Addressing these issues would definitely help us in preventing or prolonging the onset of pathogenesis of micro and macrovascular complications. Pioglitazone is used as a trusted insulin sensitizer and an adjuvant to the conventional oral hypoglycemic agents. This study was planned to explore the effects of pioglitazone on oxidative stress, serum magnesium, blood pressure, hepato-biliary and renal systems in addition to its effects on glycemic control. METHODS Sixty-three T2DM cases, who were started on pioglitazone were included in this study. All the physiological and biochemical parameters were estimated prior to and following three months of therapy with pioglitazone. RESULTS There was significant improvement in the glycemic control, serum magnesium and MDA levels with p values of 0.000, 0.023 and 0.000 respectively. Pioglitazone did not have any significant effects on the serum lipids and blood pressure in T2DM cases following three months of treatment. We did not observe any pronounced changes in hepato-biliary enzymes, serum urea and creatinine levels reaffirming safety of pioglitazone in T2DM. CONCLUSION Three-month duration of treatment with Pioglitazone in T2DM cases helps in alleviating the levels of lipid peroxides, besides being associated with improved serum magnesium status and glycemic control.
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Affiliation(s)
- G Niranjan
- Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, SBV University Pillaiyarkuppam, Puducherry 607402, India.
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125
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Koralek JD, Meier D, Hinton JP, Bauer A, Parameswaran SA, Vishwanath A, Ramesh R, Schoenlein RW, Pfleiderer C, Orenstein J. Observation of coherent helimagnons and gilbert damping in an itinerant magnet. Phys Rev Lett 2012; 109:247204. [PMID: 23368372 DOI: 10.1103/physrevlett.109.247204] [Citation(s) in RCA: 6] [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: 08/03/2012] [Indexed: 06/01/2023]
Abstract
We study the magnetic excitations of itinerant helimagnets by applying time-resolved optical spectroscopy to Fe(0.8)Co(0.2)Si. Optically excited oscillations of the magnetization in the helical state are found to disperse to lower frequency as the applied magnetic field is increased; the fingerprint of collective modes unique to helimagnets, known as helimagnons. The use of time-resolved spectroscopy allows us to address the fundamental magnetic relaxation processes by directly measuring the Gilbert damping, revealing the versatility of spin dynamics in chiral magnets.
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Affiliation(s)
- J D Koralek
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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126
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Yang JC, He Q, Suresha SJ, Kuo CY, Peng CY, Haislmaier RC, Motyka MA, Sheng G, Adamo C, Lin HJ, Hu Z, Chang L, Tjeng LH, Arenholz E, Podraza NJ, Bernhagen M, Uecker R, Schlom DG, Gopalan V, Chen LQ, Chen CT, Ramesh R, Chu YH. Orthorhombic BiFeO3. Phys Rev Lett 2012; 109:247606. [PMID: 23368382 DOI: 10.1103/physrevlett.109.247606] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/07/2012] [Indexed: 05/12/2023]
Abstract
A new orthorhombic phase of the multiferroic BiFeO3 has been created via strain engineering by growing it on a NdScO(3)(110)(o) substrate. The tensile-strained orthorhombic BiFeO3 phase is ferroelectric and antiferromagnetic at room temperature. A combination of nonlinear optical second harmonic generation and piezoresponse force microscopy revealed that the ferroelectric polarization in the orthorhombic phase is along the in-plane {110}(pc) directions. In addition, the corresponding rotation of the antiferromagnetic axis in this new phase was observed using x-ray linear dichroism.
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Affiliation(s)
- J C Yang
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan
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127
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Abstract
In the recent years, circulating nucleic acids have emerged as new biomarkers. Among these, microRNAs(miRNA) have evolved as promising and potential markers of both physiological and pathological conditions. MiRNA are transcribed from DNA like the other mRNA molecules. Their secretions and functions have to be still explored in humans, though many theories have been proposed. It is a small non coding RNA which plays an important role in the regulation of the gene expression, cell-cell communication, cell division and apoptosis. MiRNAs are stable and tissue specific and they can be identified and quantitated, which make them ideal biomarkers. This review highlights the secretion,mechanism of action and the role of miRNA in the diagnosis and the management of different disease conditions.
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Affiliation(s)
| | - R. Ramesh
- Professor & Head, Department of Biochemistry
| | - A.R. Srinivasan
- Professor, Department of Biochemistry, Mahatma Gandhi Medical College and Research Institute, Puducherry, Pin Code – 607 402, India
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128
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Abstract
The coupling and reconstruction of electronic degrees of freedom (such as charge, spin and orbital) at a heterointerface can lead to unexpected and exotic states of matter. In this study, using model systems consisting of multiferroic BiFeO(3) and ferromagnetic La(0.7)Sr(0.3)MnO(3), we review the current understanding of a novel interfacial magnetic state formed at the interface, and highlight some possible mechanisms responsible for this interesting phenomenon and identify open questions for future studies.
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Affiliation(s)
- P Yu
- Department of Physics, University of California, Berkeley, 94720, USA.
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129
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Abstract
In functional materials, nanoscale phase boundaries exhibit exotic phenomena that are notably absent in their parent phases. Over the past two decades, much of the research into complex oxides (such as cuprate superconductors, CMR manganites and relaxor ferroelectrics) has demonstrated the key role that nanoscale inhomogeneities play in controlling the electronic and/or ionic structure of these materials. One of the key characteristics in such systems is the strong susceptibility to external perturbations, such as magnetic, electric and mechanical fields. A direct consequence of the accommodation of a large number of cationic substitutions in complex oxides is the emergence of a number of physical phenomena from essentially the same crystal framework. Recently, multiferroic behavior, which is characterized by the co-existence and potential coupling of multiple ferroic order parameters, has captured considerable worldwide research interest. The perovskite, BiFeO(3), exhibits robust ferroelectricity coupled with antiferromagnetism at room temperature. A rather unique feature of this material system is its ability to "morph" its ground state when an external mechanical constraint is imposed on it. A particularly striking example is observed when a large (~4 to 5%) compressive strain is imposed on a thin film through the epitaxial constraint from the underlying substrate. Under these conditions, the ground state rhombohedral phase transforms into a tetragonal-like (or a derivative thereof) phase with a rather large unit cell (c/a ratio of ~1.26). When the epitaxial constraint is partially relaxed by increasing the film thickness, this tetragonal-like phase evolves into a "mixed-phase" state, consisting of a nanoscale admixture of the rhombohedral-like phase embedded in the tetragonal-like phase. Such a system gives us a new pathway to explore a variety of mechanical, magnetic and transport phenomena in constrained dimensions. This article reviews our progress to date in this direction and also captures some possible areas of future research. We use the electromechanical response and the magnetic properties as examples to illustrate that its novel functionalities are intrinsically due to the phase boundaries and not the constituent phases. The possible origin of the giant piezoelectric response and enhanced magnetic moment across the boundaries is proposed based on the flexoelectric and flexomagnetic effects.
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Affiliation(s)
- J X Zhang
- Department of Physics, University of California, Berkeley, California 94720, USA.
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130
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Selvam AP, Priya SL, Banerjee K, Hariharan G, Purvaja R, Ramesh R. Heavy metal assessment using geochemical and statistical tools in the surface sediments of Vembanad Lake, Southwest Coast of India. Environ Monit Assess 2012; 184:5899-5915. [PMID: 22068311 DOI: 10.1007/s10661-011-2389-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 10/03/2011] [Indexed: 05/31/2023]
Abstract
The geochemical distribution and enrichment of ten heavy metals in the surface sediments of Vembanad Lake, southwest coast of India was evaluated. Sediment samples from 47 stations in the Lake were collected during dry and wet seasons in 2008 and examined for heavy metal content (Al, Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co, Cd), organic carbon, and sediment texture. Statistically significant spatial variation was observed among all sediment variables, but negligible significant seasonal variation was observed. Correlation analysis showed that the metal content of sediments was mainly regulated by organic carbon, Fe oxy-hydroxides, and grain size. Principal component analysis was used to reduce the 14 sediment variables into three factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Pollution intensity of the Vembanad Lake was measured using the enrichment factor and the pollution load index. Severe and moderately severe enrichment of Cd and Zn in the north estuary with minor enrichment of Pb and Cr were observed, which reflects the intensity of the anthropogenic inputs related to industrial discharge into this system. The results of pollution load index reveal that the sediment was heavily polluted in northern arm and moderately polluted in the extreme end and port region of the southern arm of the lake. A comparison with sediment quality guideline quotient was also made, indicating that there may be some ecotoxicological risk to benthic organisms in these sediments.
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Affiliation(s)
- A Paneer Selvam
- Institute for Ocean Management, Anna University, Chennai, India
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131
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S RP, Ramesh R, Rachel P, Chanda R, Satish N, Mohan VR. Quality of life among people with epilepsy: a cross-sectional study from rural southern India. Natl Med J India 2012; 25:261-264. [PMID: 23448623] [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] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
BACKGROUND Epilepsy can be associated with profound physical, social and psychological consequences and it has an impact on a person's quality of life. We assessed the quality of life and factors associated with a poor quality of life, among adults with epilepsy in a rural block of Tamil Nadu. METHODS We interviewed 91 epilepsy patients from 20 randomly selected villages using a structured questionnaire including World Health Organization Quality of Life BREF (WHOQOL-BREF), Patient Health Questionnaire 2 (PHQ-2) and Generalized Anxiety Disorder 7 (GAD-7) questionnaires. RESULTS The mean (SD) total score of the quality of life scale was 61.49 (12.56). Those who were single, separated or widowed (t statistic= -2.71, p<0.01), had not completed primary education (t statistic=-2.308, p<0.05), not currently going for work (t statistic=-2.748, p<0.01), had seizure in the past one year (t statistic=-4.068, p<0.01),had depressive symptoms (t statistic=-3.207, p<0.01),had higher anxiety scores (t statistic=-2.727, p<0.01), had low scores in the quality of life questionnaire. Multivariate analysis showed increasing age, education less than grade V, being unmarried, widowed or separated, lower per capita income, a high anxiety score and experiencing a seizure episode in the past one year to be significantly associated with a low score in the WHOQOL-BREF questionnaire (adjusted R²=0.378, SE 9.90). CONCLUSION The presence of anxiety, lack of primary education, being single, separated or widowed, increasing age, low per capita income and having a seizure episode in the past year are associated with lower quality of life among people with epilepsy.
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Affiliation(s)
- Rakesh P S
- Department of Community Health, Christian Medical College, Vellore 632004, Tamil Nadu, India.
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132
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Kavitha P, Ramesh R, Bupesh G, Stalin A, Subramanian P. Hepatoprotective activity of Tribulus terrestris extract against acetaminophen-induced toxicity in a freshwater fish (Oreochromis mossambicus). In Vitro Cell Dev Biol Anim 2012; 47:698-706. [PMID: 21975853 DOI: 10.1007/s11626-011-9457-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Accepted: 09/15/2011] [Indexed: 01/11/2023]
Abstract
The potential protective role of Tribulus terrestris in acetaminophen-induced hepatotoxicity in Oreochromis mossambicus was investigated. The effect of oral exposure of acetaminophen (500 mg/kg) in O. mossambicus at 24-h duration was evaluated. The plant extract (250 mg/kg) showed a remarkable hepatoprotective activity against acetaminophen-induced hepatotoxicity. It was judged from the tissue-damaging level and antioxidant levels in liver, gill, muscle and kidney tissues. Further acetaminophen impact induced a significant rise in the tissue-damaging level, and the antioxidant level was discernible from the enzyme activity modulations such as glutamate oxaloacetic transaminase, glutamate pyruvic transaminase, alkaline phosphatase, acid phosphatase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, lipid peroxidase and reduced glutathione. The levels of all these enzymes have significantly (p < 0.05) increased in acetaminophen-treated fish tissues. The elevated levels of these enzymes were significantly controlled by the treatment of T. terrestris extract (250 kg/mg). Histopathological changes of liver, gill and muscle samples were compared with respective controls. The results of the present study specify the hepatoprotective and antioxidant properties of T. terrestris against acetaminophen-induced toxicity in freshwater fish, O. mossambicus.
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Affiliation(s)
- P Kavitha
- Department of Animal Science, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
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133
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Lubk A, Rossell MD, Seidel J, He Q, Yang SY, Chu YH, Ramesh R, Hÿtch MJ, Snoeck E. Evidence of sharp and diffuse domain walls in BiFeO3 by means of unit-cell-wise strain and polarization maps obtained with high resolution scanning transmission electron microscopy. Phys Rev Lett 2012; 109:047601. [PMID: 23006107 DOI: 10.1103/physrevlett.109.047601] [Citation(s) in RCA: 11] [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: 06/24/2011] [Indexed: 06/01/2023]
Abstract
Domain walls (DWs) substantially influence a large number of applications involving ferroelectric materials due to their limited mobility when shifted during polarization switching. The discovery of greatly enhanced conduction at BiFeO(3) DWs has highlighted yet another role of DWs as a local material state with unique properties. However, the lack of precise information on the local atomic structure is still hampering microscopical understanding of DW properties. Here, we examine the atomic structure of BiFeO(3) 109° DWs with pm precision by a combination of high-angle annular dark-field scanning transmission electron microscopy and a dedicated structural analysis. By measuring simultaneously local polarization and strain, we provide direct experimental proof for the straight DW structure predicted by ab initio calculations as well as the recently proposed theory of diffuse DWs, thus resolving a long-standing discrepancy between experimentally measured and theoretically predicted DW mobilities.
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Affiliation(s)
- A Lubk
- CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, 31055 Toulouse, France.
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134
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Misra S, Ramesh R, Ramu CS, Srirangalaxmi G, Radhakrishn H. Adrenomyeloneuropathy. J Assoc Physicians India 2012; 60:58-61. [PMID: 23405547] [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] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A 29-year-old male patient presented with progressive spastic paraparesis of three years duration. He also had gait ataxia which led to recurrent falls. In addition, there was pigmentation of the skin creases, tongue and buccal mucosa. His clinical course was remarkable by recurrent episodes of diarrhea, pulmonary tuberculosis. The investigatory work up showed a normal MRI scan of the brain, spinal cord and normal abdominal structures. The basal serum cortisol levels were low. Adrenomyeloneuropathy was diagnosed and he was started on corticosteroid supplementation. Mineralocorticoid supplementation also is planned in the follow up. The case is being presented for its rarity.
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Affiliation(s)
- S Misra
- Department of Neurology, Osmania Medical College and Osmania General Hospital, Hyderabad
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135
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Yu P, Luo W, Yi D, Zhang JX, Rossell MD, Yang CH, You L, Singh-Bhalla G, Yang SY, He Q, Ramasse QM, Erni R, Martin LW, Chu YH, Pantelides ST, Pennycook SJ, Ramesh R. Interface control of bulk ferroelectric polarization. Proc Natl Acad Sci U S A 2012; 109:9710-5. [PMID: 22647612 PMCID: PMC3382509 DOI: 10.1073/pnas.1117990109] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The control of material interfaces at the atomic level has led to novel interfacial properties and functionalities. In particular, the study of polar discontinuities at interfaces between complex oxides lies at the frontier of modern condensed matter research. Here we employ a combination of experimental measurements and theoretical calculations to demonstrate the control of a bulk property, namely ferroelectric polarization, of a heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, the control is achieved by exploiting the interfacial valence mismatch to influence the electrostatic potential step across the interface, which manifests itself as the biased-voltage in ferroelectric hysteresis loops and determines the ferroelectric state. A broad study of diverse systems comprising different ferroelectrics and conducting perovskite underlayers extends the generality of this phenomenon.
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Affiliation(s)
- P Yu
- Department of Physics, University of California, Berkeley, CA 94720, USA.
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136
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Singh A, Gandhi N, Ramesh R. Contribution of atmospheric nitrogen deposition to new production in the nitrogen limited photic zone of the northern Indian Ocean. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007737] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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137
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Kavitha P, Ramesh R, Subramanian P. Histopathological changes in Poecilia latipinna male gonad due to Tribulus terrestris administration. In Vitro Cell Dev Biol Anim 2012; 48:306-12. [PMID: 22580910 DOI: 10.1007/s11626-012-9517-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/25/2012] [Indexed: 11/25/2022]
Abstract
Tribulus terrestris is a traditionally known non-toxic aphrodisiac herb for maleness. It was experimented recently to understand the effect and mechanism on mono sex production in Poecilia latipinna. It would help to develop a new eco-friendly way to masculinize P. latipinna, since males have higher commercial value than females. The different concentration (100, 150, 200, 250 and 300 mg/L) of T. terrestris extract and a control were tested for their effect on sex transformation/reversal in P. latipinna by immersing the newly born young ones in the respective concentrations for 2 mo. The obtained results indicate that a dose dependant masculinization is obtained due to T. terrestris administration, which improved the male proportion. Histological results revealed that the testes of fish treated with T. terrestris extract contained all stages of spermatogenesis, clearly demonstrating that the administration of T. terrestris extract to P. latipinna stimulated spermatogenesis. Thus, it is discernible that 0-d-old hatchlings of P. latipinna exposed to T. terrestris extract orient/reverse their sex more towards maleness besides yielding better growth and spermatogenesis which is a mandate for fancy fish industry.
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Affiliation(s)
- P Kavitha
- Department of Animal Science, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India.
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138
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Ramesh R, Managave SR, Lekshmy PR, Laskar AH, Yadava MG, Jani RA. Comment on "Tracing the sources of water using stable isotopes: first results along the Mangalore-Udupi region, south-west coast of India". Rapid Commun Mass Spectrom 2012; 26:874-875. [PMID: 22368069 DOI: 10.1002/rcm.6174] [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: 05/31/2023]
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139
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Zhang S, Zhao YG, Li PS, Yang JJ, Rizwan S, Zhang JX, Seidel J, Qu TL, Yang YJ, Luo ZL, He Q, Zou T, Chen QP, Wang JW, Yang LF, Sun Y, Wu YZ, Xiao X, Jin XF, Huang J, Gao C, Han XF, Ramesh R. Electric-field control of nonvolatile magnetization in Co40Fe40B20/Pb(Mg(1/3)Nb(2/3))(0.7)Ti(0.3)O3 structure at room temperature. Phys Rev Lett 2012; 108:137203. [PMID: 22540724 DOI: 10.1103/physrevlett.108.137203] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Indexed: 05/31/2023]
Abstract
We report a large and nonvolatile bipolar-electric-field-controlled magnetization at room temperature in a Co(40)Fe(40)B(20)/Pb(Mg(1/3)Nb(2/3))(0.7)Ti(0.3)O(3) structure, which exhibits an electric-field-controlled looplike magnetization. Investigations on the ferroelectric domains and crystal structures with in situ electric fields reveal that the effect is related to the combined action of 109° ferroelastic domain switching and the absence of magnetocrystalline anisotropy in Co(40)Fe(40)B(20). This work provides a route to realize large and nonvolatile magnetoelectric coupling at room temperature and is significant for applications.
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Affiliation(s)
- S Zhang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
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140
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Meier D, Seidel J, Cano A, Delaney K, Kumagai Y, Mostovoy M, Spaldin NA, Ramesh R, Fiebig M. Anisotropic conductance at improper ferroelectric domain walls. Nat Mater 2012; 11:284-288. [PMID: 22367003 DOI: 10.1038/nmat3249] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 01/17/2012] [Indexed: 05/31/2023]
Abstract
Transition metal oxides hold great potential for the development of new device paradigms because of the field-tunable functionalities driven by their strong electronic correlations, combined with their earth abundance and environmental friendliness. Recently, the interfaces between transition-metal oxides have revealed striking phenomena, such as insulator-metal transitions, magnetism, magnetoresistance and superconductivity. Such oxide interfaces are usually produced by sophisticated layer-by-layer growth techniques, which can yield high-quality, epitaxial interfaces with almost monolayer control of atomic positions. The resulting interfaces, however, are fixed in space by the arrangement of the atoms. Here we demonstrate a route to overcoming this geometric limitation. We show that the electrical conductance at the interfacial ferroelectric domain walls in hexagonal ErMnO(3) is a continuous function of the domain wall orientation, with a range of an order of magnitude. We explain the observed behaviour using first-principles density functional and phenomenological theories, and relate it to the unexpected stability of head-to-head and tail-to-tail domain walls in ErMnO(3) and related hexagonal manganites. As the domain wall orientation in ferroelectrics is tunable using modest external electric fields, our finding opens a degree of freedom that is not accessible to spatially fixed interfaces.
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141
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142
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He Q, Yeh CH, Yang JC, Singh-Bhalla G, Liang CW, Chiu PW, Catalan G, Martin LW, Chu YH, Scott JF, Ramesh R. Magnetotransport at domain walls in BiFeO3. Phys Rev Lett 2012; 108:067203. [PMID: 22401116 DOI: 10.1103/physrevlett.108.067203] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Indexed: 05/31/2023]
Abstract
Domain walls in multiferroics can exhibit intriguing behaviors that are significantly different from the bulk of the material. We investigate strong magnetoresistance in domain walls of the model multiferroic BiFeO3 by probing ordered arrays of 109° domain walls with temperature- and magnetic-field-dependent transport. We observe temperature-dependent variations in the transport mechanism and magnetoresistances as large as 60%. These results suggest that by locally breaking the symmetry of a material, such as at domain walls and structural interfaces, one can induce emergent behavior with properties that deviate significantly from the bulk.
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Affiliation(s)
- Q He
- Department of Physics, University of California, Berkeley, California 94720, USA
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143
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Banerjee K, Senthilkumar B, Purvaja R, Ramesh R. Sedimentation and trace metal distribution in selected locations of Sundarbans mangroves and Hooghly estuary, northeast coast of India. Environ Geochem Health 2012; 34:27-42. [PMID: 21461887 DOI: 10.1007/s10653-011-9388-0] [Citation(s) in RCA: 12] [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] [Received: 08/11/2010] [Accepted: 03/16/2011] [Indexed: 05/30/2023]
Abstract
Four sediment cores were collected from selected locations of Sundarbans mangroves and Hooghly estuary, northeast coast of India to establish (210)Pb geochronology and trace metal distribution in sediments. Core sites were chosen to reflect a matrix of variable anthropogenic input and hydrological conditions. The vertical distribution of (210)Pb(xs) ((210)Pb(total)-(226)Ra) provided reliable geochronological age to calculate the mass accumulation rates and historic trace element inputs and their variations. The mass accumulation rates ranged from 0.41 g cm(-2) year(-1) (estuarine region) to 0.66 g cm(-2) year(-1) (mangrove region). Both in mangroves and estuarine systems, Fe-Mn oxy-hydroxides are observed to be a major controlling factor for trace metal accumulation when compared to organic carbon. Core collected from Hooghly estuary shows less contamination when compared to the mangrove region due to high energy and mostly coarse grained. Fe-normalized enrichment factors (EFs) of trace metals were calculated based on crustal trace element abundances. The EFs are typically >1 for Cd, Pb, Co, and Cu indicating that these metals are highly enriched while other metals such as Zn, Ni, Cr, and Mn show no enrichment or depletion. Both Sundarbans mangroves and Hooghly estuary have been receiving considerable pollution loads from anthropogenic sources such as industrial, domestic, and shipping activities in recent times, indicating high concentration of metals in the top few layers. This study suggests that the variation in trace metals content with depth or between mangrove and estuarine system results largely from metal input due to anthropogenic activities rather than diagenetic processes.
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Affiliation(s)
- Kakolee Banerjee
- Institute for Ocean Management, Anna University, Chennai 600025, India.
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144
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Rossell MD, Erni R, Prange MP, Idrobo JC, Luo W, Zeches RJ, Pantelides ST, Ramesh R. Atomic structure of highly strained BiFeO3 thin films. Phys Rev Lett 2012; 108:047601. [PMID: 22400888 DOI: 10.1103/physrevlett.108.047601] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Indexed: 05/31/2023]
Abstract
We determine the atomic structure of the pseudotetragonal T phase and the pseudorhombohedral R phase in highly strained multiferroic BiFeO(3) thin films by using a combination of atomic-resolution scanning transmission electron microscopy and electron energy-loss spectroscopy. The coordination of the Fe atoms and their displacement relative to the O and Bi positions are assessed by direct imaging. These observations allow us to interpret the electronic structure data derived from electron energy-loss spectroscopy and provide evidence for the giant spontaneous polarization in strained BiFeO(3) thin films.
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Affiliation(s)
- M D Rossell
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland.
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145
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146
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147
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Baek SH, Park J, Kim DM, Aksyuk VA, Das RR, Bu SD, Felker DA, Lettieri J, Vaithyanathan V, Bharadwaja SSN, Bassiri-Gharb N, Chen YB, Sun HP, Folkman CM, Jang HW, Kreft DJ, Streiffer SK, Ramesh R, Pan XQ, Trolier-McKinstry S, Schlom DG, Rzchowski MS, Blick RH, Eom CB. Giant piezoelectricity on Si for hyperactive MEMS. Science 2011; 334:958-61. [PMID: 22096193 DOI: 10.1126/science.1207186] [Citation(s) in RCA: 341] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.
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Affiliation(s)
- S H Baek
- Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706, USA
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148
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Heron JT, Trassin M, Ashraf K, Gajek M, He Q, Yang SY, Nikonov DE, Chu YH, Salahuddin S, Ramesh R. Electric-field-induced magnetization reversal in a ferromagnet-multiferroic heterostructure. Phys Rev Lett 2011; 107:217202. [PMID: 22181917 DOI: 10.1103/physrevlett.107.217202] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Indexed: 05/12/2023]
Abstract
A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.
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Affiliation(s)
- J T Heron
- Department of Materials Science and Engineering, University of California, Berkeley, 94720, USA
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149
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Zhang JX, He Q, Trassin M, Luo W, Yi D, Rossell MD, Yu P, You L, Wang CH, Kuo CY, Heron JT, Hu Z, Zeches RJ, Lin HJ, Tanaka A, Chen CT, Tjeng LH, Chu YH, Ramesh R. Microscopic origin of the giant ferroelectric polarization in tetragonal-like BiFeO(3). Phys Rev Lett 2011; 107:147602. [PMID: 22107234 DOI: 10.1103/physrevlett.107.147602] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Indexed: 05/12/2023]
Abstract
We report direct experimental evidence for a room-temperature, ∼130 μC/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.
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Affiliation(s)
- J X Zhang
- Department of Physics, University of California, Berkeley, California 94720, USA.
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150
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Krishnamoorthy P, Sathyadevi P, Senthilkumar K, Muthiah PT, Ramesh R, Dharmaraj N. Copper(I) hydrazone complexes: Synthesis, structure, DNA binding, radical scavenging and computational studies. INORG CHEM COMMUN 2011. [DOI: 10.1016/j.inoche.2011.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [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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