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Muttalib KA, Barry JH. Frustration in a generalized kagomé Ising antiferromagnet: Exact results. Phys Rev E 2022; 106:014149. [PMID: 35974653 DOI: 10.1103/physreve.106.014149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
We obtain the exact ground-state phase diagram of a generalized kagomé antiferromagnet with both pair and triplet interactions, J_{2} and J_{3}, respectively, in the presence of a magnetic field h appropriately tuned. We find that when the pair interaction J_{2}<0 dominates, the ground state is geometrically frustrated; on the other hand, the ground state is disordered but not frustrated when the triplet interaction J_{3} dominates, the boundaries between the two cases being at J_{3}=±J_{2}. The exact ground-state crossover lines between the two distinct types of disorder remain identifiable crossover curves at finite temperatures. In the frustrated domain, the ground state of the three-parameter model is identical to the ground state of the prototype one-parameter (J_{2}<0) model of geometrical frustration. Towards further understanding the frustration domain of the three-parameter model, a closed-form approximation (exact at zero temperature) determines solutions on a two-parameter subspace for induced magnetization and parallel magnetic susceptibility at finite fields h and temperatures T, the inverse susceptibility showing a Curie-Weiss behavior. We argue that the existence of an exact T=0 threshold magnetic field, below which the magnetization remains zero, indicates the existence of a gapped spectrum attributable to the presence of the triplet interaction J_{3}.
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Affiliation(s)
- K A Muttalib
- Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA
| | - J H Barry
- Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA
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Rath A, Wong M, Pannuti CM, Hesarghatta Ramamurthy P, Fernandes B, Shelton A, Muttalib KA. Cross-cultural adaptation and validation of Malay version of Rapid Estimate of Adult Literacy in Dentistry (MREALD-30) among Orang Asli population in Malaysia. BMC Oral Health 2021; 21:519. [PMID: 34641831 PMCID: PMC8513292 DOI: 10.1186/s12903-021-01866-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/28/2021] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The aim of this study was to adapt, translate and validate the Rapid Estimate of Adult Literacy in Dentistry (MREALD-30) instrument for the Orang Asli population in Malaysia. METHODS After translation and cross-cultural adaptation, interviews were conducted with 326 participants of the Temuan tribe from village Kampung Tering in Johol, Negeri Sembilan, Malaysia. The instrument's validity was assessed using the scores of MREALD-30, which were compared based on occupation, monthly household income, educational attainment, general literacy, use of dental services, and three dental outcomes. A questionnaire containing socio-behavioral information and validated Malay Oral Health Impact Profile (M-OHIP-14) was also administered. The reliability of the MREALD-30 was assessed by re-administering it to 30 subjects after two weeks. Its correlations evaluated convergent and discriminative validity of MREALD-30 with the level of education and dental visiting habits, monthly household income, respectively. Predictive validity was assessed with M-OHIP-14, while construct validity was evaluated by exploratory factor analysis using the Rasch model. RESULTS The internal consistency of the MREALD-30 measured by Cronbach's alpha was 0.89. The test-retest reliability was excellent (ICC 0.95, k = 0.85). MREALD-30 exhibited good construct validity. Rasch analysis showed two factors, and infit mean-square statistics for MREALD-30 were all within the desired range of 0.50-2.0. The discriminant validity and predictive validity were statistically significant (p < 0.05). CONCLUSIONS MREALD-30 showed very strong reliability, good construct, discriminant, and predictive validity, but poor convergent validity. Overall, it showed good psychometric properties and can be used in these community settings.
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Affiliation(s)
- Avita Rath
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia.
| | - Melissa Wong
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia
| | | | | | - Bennete Fernandes
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia
| | | | - Khairiyah Abdul Muttalib
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia
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Yadav S, Alam K, Muttalib KA, Wang D. Nonmonotonic confining potential and eigenvalue density transition for generalized random matrix model. Phys Rev E 2021; 103:042137. [PMID: 34006014 DOI: 10.1103/physreve.103.042137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 04/05/2021] [Indexed: 11/07/2022]
Abstract
We consider several limiting cases of the joint probability distribution for a random matrix ensemble with an additional interaction term controlled by an exponent γ (called the γ ensembles). The effective potential, which is essentially the single-particle confining potential for an equivalent ensemble with γ=1 (called the Muttalib-Borodin ensemble), is a crucial quantity defined in solution to the Riemann-Hilbert problem associated with the γ ensembles. It enables us to numerically compute the eigenvalue density of γ ensembles for all γ>0. We show that one important effect of the two-particle interaction parameter γ is to generate or enhance the nonmonotonicity in the effective single-particle potential. For suitable choices of the initial single-particle potentials, reducing γ can lead to a large nonmonotonicity in the effective potential, which in turn leads to significant changes in the density of eigenvalues. For a disordered conductor, this corresponds to a systematic decrease in the conductance with increasing disorder. This suggests that appropriate models of γ ensembles can be used as a possible framework to study the effects of disorder on the distribution of conductances.
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Affiliation(s)
- Swapnil Yadav
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - Kazi Alam
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - K A Muttalib
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - Dong Wang
- Department of Mathematics, National University of Singapore, Singapore 119076
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Sahani M, Sulaiman NS, Tan BS, Yahya NA, Anual ZF, Mahiyuddin WRW, Khan MF, Muttalib KA. Mercury in dental amalgam: Are our health care workers at risk? J Air Waste Manag Assoc 2016; 66:1077-1083. [PMID: 27192328 DOI: 10.1080/10962247.2016.1188866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/27/2016] [Accepted: 04/29/2016] [Indexed: 06/05/2023]
Abstract
UNLABELLED Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann-Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann-Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612-64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury. IMPLICATIONS Exposure to the high levels of mercury from dental amalgam can lead to serious health effects among the dental health care workers. Nationwide chronic mercury exposure among dental personnel was assessed through urinary mercury levels. Findings suggest low urinary mercury levels of these health care workers. Exposure to dental amalgam is not associated with high mercury exposure. However, the usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.
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Affiliation(s)
- M Sahani
- a Faculty of Health Sciences , Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz , Kuala Lumpur , Malaysia
| | - N S Sulaiman
- b Institute for Medical Research , Jalan Pahang , Kuala Lumpur , Malaysia
| | - B S Tan
- c School of Dentistry, Institute of Research , Development and Innovation, International Medical University , Kuala Lumpur , Malaysia
| | - N A Yahya
- a Faculty of Health Sciences , Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz , Kuala Lumpur , Malaysia
| | - Z F Anual
- a Faculty of Health Sciences , Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz , Kuala Lumpur , Malaysia
| | - W R Wan Mahiyuddin
- b Institute for Medical Research , Jalan Pahang , Kuala Lumpur , Malaysia
| | - M F Khan
- d Centre for Tropical Climate Change System (IKLIM), Institute of Climate Change , Universiti Kebangsaan Malaysia , Bangi , Selangor , Malaysia
| | - K A Muttalib
- e Oral Health Division , Ministry of Health , Putrajaya , Malaysia
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Sahril N, Aris T, Mohd Asari AS, Yaw SL, Saleh NC, Omar MA, Teh CH, Abdul Muttalib K, Idzwan MF, Low LL, Junid NZ, Ismail F, Ismail NA, Abu Talib N. Oral health seeking behaviour among Malaysians with type II diabetes. ACTA ACUST UNITED AC 2014. [DOI: 10.7243/2055-7205-1-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [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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Misra R, Hebard AF, Muttalib KA, Wölfle P. Asymmetric metal-insulator transition in disordered ferromagnetic films. Phys Rev Lett 2011; 107:037201. [PMID: 21838396 DOI: 10.1103/physrevlett.107.037201] [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] [Received: 03/22/2010] [Indexed: 05/31/2023]
Abstract
We present experimental data and a theoretical interpretation of the conductance near the metal-insulator transition in thin ferromagnetic Gd films of thickness b ≈ 2-10 nm. A large phase relaxation rate caused by scattering of quasiparticles off spin-wave excitations renders the dephasing length L(ϕ) ≲ b in the range of sheet resistances considered, so that the effective dimension is d = 3. The conductivity data at different stages of disorder obey a fractional power-law temperature dependence and collapse onto two scaling curves for the metallic and insulating regimes, indicating an asymmetric metal-insulator transition with two distinctly different critical exponents; the best fit is obtained for a dynamical exponent z ≈ 2.5 and a correlation (localization) length critical exponent ν- ≈ 1.4 (ν+ ≈ 0.8) on the metallic (insulating) side.
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Affiliation(s)
- R Misra
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
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Barry JH, Muttalib KA, Tanaka T. Solutions for correlations along the coexistence curve and at the critical point of a kagomé lattice gas with three-particle interactions. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:011102. [PMID: 18351813 DOI: 10.1103/physreve.77.011102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Indexed: 05/26/2023]
Abstract
We consider a two-dimensional (d=2) kagomé lattice gas model with attractive three-particle interactions around each triangular face of the kagomé lattice. Exact solutions are obtained for multiparticle correlations along the liquid and vapor branches of the coexistence curve and at criticality. The correlation solutions are also determined along the continuation of the curvilinear diameter of the coexistence region into the disordered fluid region. The method generates a linear algebraic system of correlation identities with coefficients dependent only upon the interaction parameter. Using a priori knowledge of pertinent solutions for the density and elementary triplet correlation, one finds a closed and linearly independent set of correlation identities defined upon a spatially compact nine-site cluster of the kagomé lattice. Resulting exact solution curves of the correlations are plotted and discussed as functions of the temperature and are compared with corresponding results in a traditional kagomé lattice gas having nearest-neighbor pair interactions. An example of application for the multiparticle correlations is demonstrated in cavitation theory.
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Affiliation(s)
- J H Barry
- Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA
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Muttalib KA, Ismail MEH. Power-law eigenvalue density, scaling, and critical random-matrix ensembles. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:051105. [PMID: 18233621 DOI: 10.1103/physreve.76.051105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Indexed: 05/25/2023]
Abstract
We consider a class of rotationally invariant unitary random matrix ensembles where the eigenvalue density falls off as an inverse power law. Under a scaling appropriate for such power-law densities (different from the scaling required in Gaussian random matrix ensembles), we calculate exactly the two-level kernel that determines all eigenvalue correlations. We show that such ensembles belong to the class of critical ensembles.
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Affiliation(s)
- K A Muttalib
- Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA.
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Mitra P, Misra R, Hebard AF, Muttalib KA, Wölfle P. Weak-localization correction to the anomalous Hall effect in polycrystalline fe films. Phys Rev Lett 2007; 99:046804. [PMID: 17678389 DOI: 10.1103/physrevlett.99.046804] [Citation(s) in RCA: 9] [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: 06/08/2006] [Indexed: 05/16/2023]
Abstract
In situ transport measurements have been made on ultrathin (<100 A thick) polycrystalline Fe films as a function of temperature and magnetic field for a wide range of disorder strengths. For sheet resistances Rxx less than approximately 3kOmega, we find a logarithmic temperature dependence of the anomalous Hall conductivity sigmaxy, which is shown for the first time to be due to a universal scale dependent weak-localization correction within the skew-scattering model. For higher sheet resistance, granularity becomes important and the break down of universal behavior becomes manifest as the prefactors of the lnT correction term to sigmaxx and sigmaxy decrease at different rates with increasing disorder.
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Affiliation(s)
- P Mitra
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
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Muttalib KA, Klauder JR. Family of solvable generalized random-matrix ensembles with unitary symmetry. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 71:055101. [PMID: 16089584 DOI: 10.1103/physreve.71.055101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Indexed: 05/03/2023]
Abstract
We construct a very general family of characteristic functions describing random matrix ensembles (RME) having a global unitary invariance, and containing an arbitrary, one-variable probability measure, which we characterize by a "spread function." Various choices of the spread function lead to a variety of possible generalized RMEs, which show deviations from the well-known Gaussian RME originally proposed by Wigner. We obtain the correlation functions of such generalized ensembles exactly and show examples of how particular choices of the spread function can describe ensembles with arbitrary eigenvalue densities as well as critical ensembles with multifractality.
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Affiliation(s)
- K A Muttalib
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
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Nik-Hussein NN, Abdul Muttalib K, Junid NZ, Wan MNWO, Abang A. Oral health status of 16-year-old school children in Malaysia. Singapore Dent J 2004; 26:30-8. [PMID: 15736839] [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: 05/01/2023]
Abstract
The aim of the present study was to determine the oral health status of 16-year-old Malaysian school children. The prevalence of caries was 75.5%. More than 60% of subjects had caries experience by teeth (DMFT) scores of 0-3. The largest component of the DMFT and caries experience by surface index was the filled component. Females had higher caries prevalence and caries scores than males. The mouth and tooth prevalences of enamel defects were 56% and 21.8%, respectively. The most common type of enamel defects observed were diffuse opacities, affecting 95.5% of affected subjects and 92.1% of affected teeth. One-third of subjects had healthy gingival conditions, 8.6% had bleeding gingivae, 55.1% had calculus and 3% had pockets. Less than 1% of subjects wore or required dentures. Cleft lip and/or palate was uncommon. This study shows that the prevalence of caries and DMFT scores have declined over the last 30 years.
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Affiliation(s)
- Nik Noriah Nik-Hussein
- Department of Children's Dentistry and Orthodontics, Dental Faculty, University of Malaya, Kuala Lumpur, Malaysia.
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Abstract
The present day non-gaussian distribution of mass density of the universe evolved from an initial gaussian distribution in the presence of nonlinear interactions. We discuss an analog in disordered condensed matter system where increasing the disorder changes the distribution of conductances from a gaussian at weak disorder to a log-normal at strong disorder. The highly asymmetric "one-sided" log-normal distribution in the intermediate crossover regime can be understood as a simple hybrid of these two limiting distributions.
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Affiliation(s)
- K A Muttalib
- Department of Physics, University of Florida, P.O. Box 118440, Gainesville, FL 32611-8440, USA.
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Muttalib KA, Pichard J, Stone AA. Random-matrix theory and universal statistics for disordered quantum conductors. Phys Rev Lett 1987; 59:2475-2478. [PMID: 10035560 DOI: 10.1103/physrevlett.59.2475] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Gray KE, Kampwirth RT, Rosenbaum TF, Field SB, Muttalib KA. Weak localization in superconductors: A study of radiation-damaged Nb3Ir. Phys Rev B Condens Matter 1987; 35:8405-8412. [PMID: 9941189 DOI: 10.1103/physrevb.35.8405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Browne DA, Levin K, Muttalib KA. Coulomb-induced anomalies in highly disordered superconductors: Application to tunneling. Phys Rev Lett 1987; 58:156-159. [PMID: 10034617 DOI: 10.1103/physrevlett.58.156] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Coffey L, Levin K, Muttalib KA. Upper critical field of strongly disordered three-dimensional superconductors: Localization effects. Phys Rev B Condens Matter 1985; 32:4382-4391. [PMID: 9937617 DOI: 10.1103/physrevb.32.4382] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Rosenbaum TF, Field SB, Muttalib KA. Scaling behavior of amorphous FeMn in magnetic fields. Phys Rev B Condens Matter 1985; 32:4804-4806. [PMID: 9937678 DOI: 10.1103/physrevb.32.4804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Muttalib KA, Sethna J. Coverage dependence and isotope effect in quantum surface diffusion. Phys Rev B Condens Matter 1985; 32:3462-3464. [PMID: 9937487 DOI: 10.1103/physrevb.32.3462] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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