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Johns Hopkins Center on Aging and Health
Selected Publications

Varadhan R, Gilbert P.  BB: An R Package for Solving a Large System of Nonlinear Equations and for Optimizing a High-Dimensional Nonlinear Objective Function. J Stat Soft. 2009 Oct;32(4):1-26.

Varadhan R, Chaves PH, Lipsitz LA, Stein PK, Tian J, Windham BG, Berger RD,Fried LP. Frailty and impaired cardiac autonomic control: new insights fromprincipal components aggregation of traditional heart rate variability indices. JGerontol A Biol Sci Med Sci. 2009 Jun;64(6):682-7. Epub 2009 Feb 17.

Alipanah N, Varadhan R, Sun K, Ferrucci L, Fried LP, Semba RD. Low serum carotenoids are associated with a decline in walking speed in older women. J NutrHealth Aging. 2009 Mar;13(3):170-5.

Fried LP, Xue QL, Cappola AR, Ferrucci L, Chaves P, Varadhan R, Guralnik JM, Leng SX, Semba RD, Walston JD, Blaum CS, Bandeen-Roche K. Nonlinear Multisystem Physiological Dysregulation Associated With Frailty in Older Women: Implications for Etiology and Treatment. J Gerontol A Biol Sci Med Sci. 2009 Jul 21. [Epub ahead of print].

Chaves PH, Varadhan R, Lipsitz LA, Stein PK, Windham BG, Tian J, Fleisher LA, Guralnik JM, Fried LP. Physiological complexity underlying heart rate dynamics and frailty status in community-dwelling older women. J Am Geriatr Soc. 2008 Sep;56(9):1698-703.

Varadhan R, Seplaki C, Xue QL, Bandeen-Roche K, Fried LP.  Stimulus-response paradigm for characterizing the loss of resilience in homeostatic regulation associated with frailty.  Mechanisms of Ageing and Development; [Epub ahead of print]

Fried LP, Varadhan R, Bohr VA. Opinion section on frailty. Mech Ageing Dev. 2008 Nov;129(11):665. Epub 2008 Oct 4.

Varadhan R, and Roland C (2008).   Simple and Globally Convergent Methods for Accelerating the Convergence of Any EM Algorithm S cand J Statist

Varadhan R, Walston J, Cappola AR, Carlson MC, Wand GS, Fried LP (2008). Higher levels and blunted diurnal variation of cortisol in frail older women.J Gerontol A Biol Sci Med Sci.  Feb;63(2):190-5.

Roland Ch., Varadhan R and Frangakis CE.  (2007).Squared polynomial extrapolation methods with cycling: an application to the positron emission tomography problem.  Numerical Algorithms.  Feb;44(2):159-172

Roland Ch., and Varadhan R (2005), New iterative schemes for nonlinear fixed point problems with applications to problems with bifurcations and incomplete-data problems, Applied Numerical Mathematics, 55(2), 215-226.Y.

Fujiwara Y, Chaves PHM, Takahashi R, Amano H, Kumagai S, Fujita K, Yoshida H, Wang DG, Varadhan R, Uchida H, Shinkai S (2004). Relationships between arterial pulse wave velocity and conventional Atherosclerotic risk factors in community-dwelling people. Preventive Medicine, 39, 1135-42.

Li F, Frangakis CE, and Varadhan R (2004). Polydesigns in causal inference. Proceedings of the American Statistical Association, Section on Statistics in Epidemiology.

Varadhan R, and Frangakis, CE (2004), Revealing and addressing length bias and heterogeneous effects in frequency case-crossover studies, American Journal of Epidemiology, 159(6), 596-602.

Frangakis CE and Varadhan R (2004), Systematizing the evaluation of partially controlled studies using principal stratification: from theory to practice, Statistica Sinica, 14, 945-947.

Frangakis CE, Brookmeyer RS, Varadhan R, Mahboobeh S, Vlahov D, and Strathdee SA (2004). Methodology for evaluating a partially controlled longitudinal treatment using principal stratification, with application to a Needle Exchange Program, Journal of American Statistical Association, 98, 239-249.

Frangakis CE and Varadhan R (2002), Confidence intervals for seasonal relative risk with null boundary values, Epidemiology, 13(6), 734-737.

DiGiulio DC and Varadhan R (2000). Steady-state field-scale gas permeability estimation and pore-gas velocity calculation in a domain open to the atmosphere, Remediation, autumn issue.

DiGiulio DC, Brusseau ML, and Varadhan Ravi (1999). Evaluation of mass flux to and from ground water using a vertical flux model (VFLUX): Application to the soil vacuum extraction closure problem, Ground Water Monitoring and Remediation, 21(1), 97-114.

Varadhan Ravi, Chen JS, Wilson JT, Johnson JA, Gierke W, and Murdie L (1998). Evaluation of natural attenuation of benzene and dichloroethanes at the KL landfill, Bioremediation Journal, 2, 239-258.

Johnson JA, Varadhan Ravi, and Rumery JK (1994). Estimation of solute concentrations using the path counting method, Ground Water, 32, 719-726.

Jennings AA and Varadhan Ravi (1992). Interface penetration model formulation for analyzing wall-separation-influenced transient hydraulic conductivity data, Soil Science Society of America Journal, 56, 1023-1032.

Varadhan Ravi and Jennings AA (1990). Penetration model parameter estimation from dynamic permeability measurements, Soil Science Society of America Journal, 54, 13-19.

Jennings AA and Varadhan Ravi (1990). Analytic extensions of the discrete interface penetration model for dynamic permeability analysis, Soil Science Society of America Journal, 54, 7-12.

Varadhan Ravi and Jennings AA (1990). Monte Carlo techniques applied to parameter estimation for permeability-altering soil/permeant interaction models, (In) Computer Techniques in Environmental Studies III, (ed.) Zannetti P, Springer-Verlag, NY.

Book Chapters and Peer-Reviewed Reports
Varadhan R, and Roland Ch. (2004), Squared extrapolation methods (SQUAREM): A new class of simple and efficient numerical schemes for accelerating the convergence of the EM algorithm, Johns Hopkins University, Department of Biostatistics Working Papers, paper 63,

DiGiulio DC and Varadhan R (2001). Development of Recommendations and Methods to Support Soil Venting Performance and Closure, Report published by US EPA, ORD, EPA/600/R-01/070.

Williams JR, Ouyang Y, Chen JS, and Varadhan Ravi (1998). Estimation of Infiltration Rate in the Vadose Zone: Application of Selected Models, Report published by US EPA, ORD, EPA/600/R-97/128b.

Varadhan Ravi and Williams JR (1998). Estimation of Infiltration Rate in the Vadose Zone: Compilation of Simple Mathematical Models, Report published by US EPA, ORD, EPA/600/R-97/128a.

Jennings AA, and Varadhan Ravi (1994). Mechanisms and models for aggressive permeant interactions with soils, (In) Environmental Modelling Vol.II, Chapter 8, 213-275, Computational Mechanics Publications, Boston.

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