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Subrammaniyan R, Amalorpavanathan J, Shankar R, Rajkumar M, Baskar S, Manjunath S, Senthilkumar R, Abraham S. Our experience of application of Autologous Bone Marrow Stem Cells in critical limb ischemia in six diabetic patients - A five-year follow-up. J Stem Cells Regen Med 2011; 7:97. [PMID: 24693184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
BACKGROUND Numerous Clinical studies have reported the safety and efficacy of injection of one Marrow and Peripheral Blood Mononuclear cells in patients with lower limb ischemia. Earlier we have reported the six months follow-up of successful application of autologous bone marrow mononuclear cells in patients with Fontaine Stage IV critical limb ischemia due to diabetes. As a continuation of the previous study, herein we report the long term results of the six patients after a follow-up for five years. MATERIALS & METHODS Six Diabetic patients with Fontaine Stage IV critical limb ischemia with ulcers were given intra-lesional injections of their autologous bone marrow mononuclear cells (BMMNC), isolated following the cGMP protocols. The patients have been followed up at regular intervals for five years after the treatment with all relevant clinical investigations. RESULTS Six months follow-up results revealed that all the patients showed improvements with appearance of healthy granulation tissue and uniform revascularization. Complete healing was reported at a mean duration of nine months in five patients and one patient died due to a complication of renal failure, peritoneal dialysis and cardiac failure, which were unrelated to the BMMNC injection. Five year continuous follow-up revealed that the healed tissue with or without skin grafting remained healthy in all the five patients and two of the patients are able to walk without support with a pain free walking distance of greater than 100m.There were no adverse effects in any of the patients.. CONCLUSION Autologous bone marrow stem cell therapy has been found to be salvaging the affected limb in patients with Fontaine Stage IV Critical Limb ischemia patients where revascularization was not feasible. Hence with our experience of six patients we recommend that the same should be considered in patients of similar clinical parameters before considering an amputation.
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Shankar R, Vishwanath A. Equality of bulk wave functions and edge correlations in some topological superconductors: a spacetime derivation. PHYSICAL REVIEW LETTERS 2011; 107:106803. [PMID: 21981520 DOI: 10.1103/physrevlett.107.106803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Indexed: 05/31/2023]
Abstract
For certain systems, the N-particle ground-state wave functions of the bulk happen to be exactly equal to the N-point spacetime correlation functions at the edge, in the infrared limit. We show why this had to be so for a class of topological superconductors, beginning with the p+ip state in D=2+1. Varying the chemical potential as a function of Euclidean time between weak and strong pairing states is shown to extract the wave function. Then a Euclidean rotation that exchanges time and space and approximate Lorentz invariance lead to the edge connection. This framework readily generalizes to other dimensions. We illustrate it with a D=3+1 example, superfluid 3He- B, and a p-wave superfluid in D=1+1. Our method works only when the particle number is not conserved, as in superconductors.
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Shankar R, Bajracharya O, Jha N, Gurung SB, Ansari SR, Thapa HS. Change in medical students' readiness for self-directed learning after a partially problem-based learning first year curriculum at the KIST medical college in Lalitpur, Nepal. EDUCATION FOR HEALTH (ABINGDON, ENGLAND) 2011; 24:552. [PMID: 22081659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Modern medical education and the requirement for lifelong learning place increasing emphasis on self-directed learning. Studies have not been done on readiness for self-directed learning (SDL) among medical students in Nepal. The present study was carried out to (1) measure and compare readiness for SDL among medical students, and (2) note differences in readiness for SDL according to students' personal characteristics at the beginning and end of the first year of the MBBS course for medical students at the KIST Medical College in Nepal. METHODS The study was done using the Self-directed Learning Readiness Scale. Respondents' agreement with each of forty statements pertinent to self-directed learning readiness using a modified Likert-type scale was noted. The mean total and scores on the subcategories 'self-management', 'desire for learning' and 'self-control' were calculated and compared across subgroups of respondents and in January and August 2010 using appropriate parametric and non-parametric tests (p<0.05). RESULTS All 100 students participated in January while 90 participated in August. The mean scores varied with certain demographic and background characteristics. The mean total score increased from 152.7 to 157.3 while the self-management score increased significantly from 48.6 to 50.2 from January to August. There were small increases in the mean desire for learning scores from 46.9 to 47.7 and in the self-control scores from 58 to 59 from January to August, but not in other scores. CONCLUSIONS Self-directed learning scores were lower among these Nepalese students than reported elsewhere in the literature. Total scores and self-management scores improved at the end of the first year, but not scores on desire for learning and self-control.
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Shankar R. Renormalization group for non-relativistic fermions. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:2612-2624. [PMID: 21646269 DOI: 10.1098/rsta.2010.0385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A brief introduction is given to the renormalization group for non-relativistic fermions at finite density. It is shown that Landau's theory of the Fermi liquid arises as a fixed point (with the Landau parameters as marginal couplings) and its instabilities as relevant perturbations. Applications to related areas, nuclear matter, quark matter and quantum dots, are briefly discussed. The focus will be on explaining the main ideas to people in related fields, rather than addressing the experts.
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Malaviya P, Singh RP, Singh SP, Hasker E, Ostyn B, Shankar R, Boelaert M, Sundar S. Monitoring drug effectiveness in kala-azar in Bihar, India: cost and feasibility of periodic random surveys vs. a health service-based reporting system. Trop Med Int Health 2011; 16:1159-66. [PMID: 21624015 DOI: 10.1111/j.1365-3156.2011.02803.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE In 2009, a random survey was conducted in Muzaffarpur district to document the clinical outcomes of visceral leishmaniasis patients (VL) treated by the public health care system in 2008, to assess the effectiveness of miltefosine against VL. We analysed the operational feasibility and cost of such periodic random surveys as compared with health facility-based routine monitoring. METHODS A random sample of 150 patients was drawn from registers kept at Primary Health Care centres. Patient records were examined, and the patients were located at their residence. Patients and physicians were interviewed with the help of two specifically designed questionnaires by a team of one supervisor, one physician and one field worker. Costs incurred during this survey were properly documented, and vehicle log books maintained for analysis. RESULTS Hundred and 39 (76.7%) of the patients could be located. Eleven patients were not traceable. Per patient, follow-up cost was US$ 15.51 and on average 2.27 patients could be visited per team-day. Human resource involvement constituted 75% of the total cost whereas involvement of physician costs 51% of the total cost. CONCLUSION A random survey to document clinical outcomes is costly and labour intensive but gives probably the most accurate information on drug effectiveness. A health service-based retrospective cohort reporting system modelled on the monitoring system developed by tuberculosis programmes could be a better alternative. Involvement of community health workers in such monitoring would offer the additional advantage of treatment supervision and support.
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Kumar U, Shankar R, Wagh M, Madhubabu M, Vembu N. A Concise and Cascade Synthesis of Batracylin and Substituted Isoindolo-[1,2-b]quinazolin-12(10H)-ones. Synlett 2011. [DOI: 10.1055/s-0030-1259921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Hasker E, Singh SP, Malaviya P, Singh RP, Shankar R, Boelaert M, Sundar S. Management of visceral leishmaniasis in rural primary health care services in Bihar, India. Trop Med Int Health 2011; 15 Suppl 2:55-62. [PMID: 20591081 DOI: 10.1111/j.1365-3156.2010.02562.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE In 2005 a visceral leishmaniasis (VL) elimination initiative was launched on the Indian subcontinent, with early diagnosis based on a rapid diagnostic test and treatment with the oral drug miltefosine as its main strategy. Several recent studies have signaled underreporting of VL cases in the region. Information on treatment outcomes is scanty. Our aim was to document VL case management by the primary health care services in India. METHODS We took a random sample of all VL patients registered in rural primary health care (PHC) facilities of Muzaffarpur district, Bihar, India during 2008. Patients were traced at home for an interview and their records were reviewed. We recorded patient and doctor delay, treatment regimens, treatment outcomes and costs incurred by patients. RESULTS We could review records of all 150 patients sampled and interview 139 patients or their guardian. Most patients (81%) had first presented to unqualified practitioners; median delay before reaching the appropriate primary healthcare facility was 40 days (IQR 31-59 days). Existing networks of village health workers were under-used. 48% of VL patients were treated with antimonials; 40% of those needed a second treatment course. Median direct expenditure by patients was 4000 rupees per episode (IQR 2695-5563 rupees), equivalent to almost 2 months of household income. CONCLUSION In 2008 still critical flaws remained in VL case management in the primary health care services in Bihar: obsolete use of antimonials with high failure rates and long patient delay. To meet the target of the VL elimination, more active case detection strategies are needed, and village health worker networks could be more involved. Costs to patients remain an obstacle to early case finding.
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Kumar U, Wagh M, Shankar R, Gill C. A Concise and Convergent Synthesis of Luotonin B and E. Synlett 2010. [DOI: 10.1055/s-0030-1259098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Shankar R, Kolandaivel P, Senthilkumar L. Interaction studies of cysteine with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ metal cation complexes. J PHYS ORG CHEM 2010. [DOI: 10.1002/poc.1786] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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85
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Dhochak K, Shankar R, Tripathi V. Magnetic impurities in the honeycomb Kitaev model. PHYSICAL REVIEW LETTERS 2010; 105:117201. [PMID: 20867601 DOI: 10.1103/physrevlett.105.117201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 08/12/2010] [Indexed: 05/29/2023]
Abstract
We study the effect of coupling magnetic impurities to the honeycomb lattice spin-1/2 Kitaev model in its spin-liquid phase. We show that a spin-S impurity coupled to the Kitaev model is associated with an unusual Kondo effect with an intermediate coupling unstable fixed point Kc∼J/S separating topologically distinct sectors of the Kitaev model. We also show that the massless spinons in the spin-liquid mediate an interaction of the form Siα2Sjβ2/Rij3 between distant impurities unlike the usual dipolar RKKY interaction SiαSjα/Rij3 noted in various 2D impurity problems with a pseudogapped density of states of the spin bath. Furthermore, this long-range interaction is possible only if the impurities (a) couple to more than one neighboring spin on the host lattice and (b) the impurity spin S≠1/2.
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Ramesh A, Banwet D, Shankar R. Modeling the barriers of supply chain collaboration. JOURNAL OF MODELLING IN MANAGEMENT 2010. [DOI: 10.1108/17465661011061014] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Prabhu A, Saini D, Patadiya B, Shankar R. SU-GG-T-531: A Unique Method for End-To-End Quality Assurance Test for Trigeminal Neuralgia Treatments in CyberKnife. Med Phys 2010. [DOI: 10.1118/1.3468928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Mondal S, Sen D, Sengupta K, Shankar R. Tuning the conductance of dirac fermions on the surface of a topological insulator. PHYSICAL REVIEW LETTERS 2010; 104:046403. [PMID: 20366724 DOI: 10.1103/physrevlett.104.046403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Indexed: 05/29/2023]
Abstract
We study the transport properties of the Dirac fermions with a Fermi velocity v{F} on the surface of a topological insulator across a ferromagnetic strip providing an exchange field J over a region of width d. We show that the conductance of such a junction, in the clean limit and at low temperature, changes from oscillatory to a monotonically decreasing function of d beyond a critical J. This leads to the possible realization of a magnetic switch using these junctions. We also study the conductance of these Dirac fermions across a potential barrier of width d and potential V0 in the presence of such a ferromagnetic strip and show that beyond a critical J, the criteria of conductance maxima changes from chi=eV{0}d/variant Planck's over v{F}=npi to chi=(n+1/2)pi for integer n. We point out that these novel phenomena have no analogs in graphene and suggest experiments which can probe them.
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Candiotti K, Sharma S, Shankar R. Obesity, obstructive sleep apnoea, and diabetes mellitus: anaesthetic implications. Br J Anaesth 2009; 103 Suppl 1:i23-30. [DOI: 10.1093/bja/aep294] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Senthil T, Shankar R. Fermi surfaces in general codimension and a new controlled nontrivial fixed point. PHYSICAL REVIEW LETTERS 2009; 102:046406. [PMID: 19257450 DOI: 10.1103/physrevlett.102.046406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Indexed: 05/27/2023]
Abstract
The energy of a d-dimensional Fermi system typically varies only along d(c)=1 ("radial") dimensions. We consider d(c)=1+epsilon and study a transition to superconductivity in an epsilon expansion. The nontrivial fixed point describes a scale invariant theory with an effective space-time dimension D=d(c)+1. Remarkably, the results can be reproduced by the Hertz-Millis action for the superconducting order parameter in higher effective space-time dimensions. We consider possible realizations of the transition at epsilon=1, which corresponds to a linear Fermi surface in d=3.
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Syam Kumar U, Shanmugapriya D, Shankar R, Satyanarayana G, Dahanukar V, Vembu N. Aerial Oxidation of 2,2-Dibromo-1-Aryl and Heteroaryl Ethanones: A Facile Synthesis of Aryl and Heteroaryl α-Keto Amides. Synlett 2008. [DOI: 10.1055/s-0028-1087353] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Dutta SB, Shankar R. Bosonization, coherent states and semiclassical quantum Hall skyrmions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:275237. [PMID: 21694398 DOI: 10.1088/0953-8984/20/27/275237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We bosonize (2+1)-dimensional fermionic theory using coherent states. The gauge-invariant subspace of boson-Chern-Simons Hilbert space is mapped to fermionic Hilbert space. This subspace is then equipped with a coherent state basis. These coherent states are labelled by a dynamic spinor field. The label manifold could be assigned a physical meaning in terms of density and spin density. A path-integral representation of the evolution operator in terms of these physical variables is given. The corresponding classical theory when restricted to LLL is described by spin fluctuations alone and is found to be the NLSM with Hopf term. The formalism developed here is suitable to study quantum Hall skyrmions semiclassically and/or beyond the hydrodynamic limit. The effects of Landau level mixing or the presence of slowly varying external fields can also be easily incorporated.
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Abstract
BACKGROUND Appendectomy is one of the commonest procedures in surgery. In spite of various investigations used to improve the accuracy of diagnosis, the rate of normal appendices removed is still about 15-30%. Many studies have investigated the role of C-reactive protein (CRP) in acute appendicitis, but with conflicting results. METHODS In a prospective, double blind study, blood for the measurement of serum C-reactive protein was collected pre-operatively from 192 children before going to the operating theatre for appendectomy. The histopathology was grouped into positive (acute appendicitis) and negative (normal appendix) and this was correlated with CRP values. RESULTS CRP was normal in 14 out of 33 negative explorations (normal appendix on histopathology). The specificity and sensitivity of serum CRP was 42% and 91% respectively. The predictive value of a positive (raised CRP) and negative (normal CRP) test is 88% and 48% respectively. CONCLUSION We conclude that neither raised nor normal CRP value is helpful in the diagnosis of acute appendicitis. CRP is not a good tool for helping the surgeon make the diagnosis of appendicitis and it should not be measured in suspected appendicitis.
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Ramesh A, Banwet D, Shankar R. Modelling the enablers of supply chain collaboration. ACTA ACUST UNITED AC 2008. [DOI: 10.1504/ijlsm.2008.019182] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Subrammaniyan S, Rajkumar M, Amalopavanathan J, Shankar R, Manjunath S, Senthil Kumar R, Abraham S. Our Experience in treating Ischemic Ulcer of a Lower Limb in 4 diabetic patients with Autologous Bone Marrow Stem Cells. J Stem Cells Regen Med 2007; 3:30-31. [PMID: 24693022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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96
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Jain R, Singh G, Shankar R. A comparative evaluation of bone regeneration in osseous defects using hydroxyapatite graft and the extent of ossification in osseous defects treated without grafts. Int J Oral Maxillofac Surg 2007. [DOI: 10.1016/j.ijom.2007.08.175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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97
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Baskaran G, Mandal S, Shankar R. Exact results for spin dynamics and fractionalization in the Kitaev Model. PHYSICAL REVIEW LETTERS 2007; 98:247201. [PMID: 17677986 DOI: 10.1103/physrevlett.98.247201] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Indexed: 05/16/2023]
Abstract
We present certain exact analytical results for dynamical spin correlation functions in the Kitaev Model. It is the first result of its kind in nontrivial quantum spin models. The result is also novel: in spite of the presence of gapless propagating Majorana fermion excitations, dynamical two spin correlation functions are identically zero beyond nearest neighbor separation. This shows existence of a gapless but short range spin liquid. An unusual, all energy scale fractionalization of a spin-flip quanta, into two infinitely massive pi fluxes and a dynamical Majorana fermion, is shown to occur. As the Kitaev Model exemplifies topological quantum computation, our result presents new insights into qubit dynamics and generation of topological excitations.
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Shankar R, Kolandaivel P, Nirmala V, Narayandass SK. Molecular Interaction of H 2, N 2, and HF Molecules with the Silicon Carbide (SiC) n=5−9 Clusters: A Theoretical Study. ACTA ACUST UNITED AC 2007. [DOI: 10.1166/jctn.2007.2368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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99
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Lukose V, Shankar R, Baskaran G. Novel electric field effects on Landau levels in graphene. PHYSICAL REVIEW LETTERS 2007; 98:116802. [PMID: 17501075 DOI: 10.1103/physrevlett.98.116802] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Indexed: 05/15/2023]
Abstract
A new effect in graphene in the presence of crossed uniform electric and magnetic fields is predicted. Landau levels are shown to be modified in an unexpected fashion by the electric field, leading to a collapse of the spectrum, when the value of electric to magnetic field ratio exceeds a certain critical value. Our theoretical results, strikingly different from the standard 2D electron gas, are explained using a "Lorentz boost," and as an "instability of a relativistic quantum field vacuum." It is a remarkable case of emergent relativistic type phenomena in nonrelativistic graphene. We also discuss few possible experimental consequence.
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Shankar S, Shankar R, Considine R, Steinberg H. Effects of Insulin and Free Fatty Acids on Asymmetric Dimethyl Arginine, a Novel Cardiovascular Risk Factor. J Investig Med 2007. [DOI: 10.1177/108155890705500260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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