Adriano M. Alencar, PhD.
Research Associate -- Harvard School of Public Health (HSPH)
Web Page: Adriano Alencar
Phone: (617) 353 6861
e-mail: adriano@bu.edu
Links
  • Curriculum (full version)
    • Invited Seminars
      • 2002 - Acoustics in the Lung, Medical School, Universidade de Sao Paulo (USP), Brazil (Slides)
      • 2002 - instabilities in the lung: negative stiffness, crackle sound, and molecular dynamics of liquid bridge formation Biomechanics Seminar, Boston University (Slides)
      • 2003 - Sufactante, Surface Tension and Energy Released During Lung Recruitment Medical School / Hospital do Coração, Universidade de São Paulo (USP) (Slides) .
      • 2004 - Airway Openings in the Lung: Microscopic Physics to Macroscopic Signals New England Complex Sistems Institute (Slides)
    • Publications and PDF download
    • Selected Oral Presentation in Conferences
      • 2001 STATPHYS XXI, Cancum, Crackles (Slides)
      • 2002 ATS, Atlanta , Negative Elastance (Slides)
      • 2002 ATS, Atlanta, Crackles (Slides)
      • 2003 - " A Monte Carlo Model of the Airway Opening and Analytical Results of Liquid Bridge Instabilities", Biomedical Engineering Society, Nashville - TN, Monte Carlo
      • 2004 - "Effects of stretching on the dynamics of a single polymer chain", Biomedical Engineering Society, Philadelphia, Monte Carlo
  • Colaborations
  • Link to Several Scientific tools

Research Interest

Acoustic in branched structure, in particular generation and propagation of pulmonary crackle sound; Thermodynamic out of equilibrium and critical phenomena; Dynamic of anphiphilic molecules, in particular lung surfactant; Self Organized Criticality; and Percolation.

Research Projects

[Figure caption] Example of the P-Vcurve (abstract) during the inflation of a degassed rat lung. Inset, magnification of a region with many local negative-elastance patterns.
Current Research

The lung is the bigest acoustic instrument of the our body and the sound it generates has long been used to clinical diagnosis. Among the many lung sounds generated in the airways in a diseased lung during breathing crackles is one of the most important for diagnosis. Pressure-volume (P-V) and pressure-flow curves are of the standard mechanical test of the lung and are crutial to the control of mechanical ventilators for live support. Lungs are coated with a thin liquid layer of a liquid called lung surfactant holding some physical properties that makes breathing possible. Small changes on its properties generates thermodynamic instabilities and may be closely associated with the generation of sound.
My current research has its goal to connect macroscopic meassurements of the lung, such as crackle sound and P-V curve, to the molecular level models of the liquid that coat the internal surface of the lung.
Methods:
  • Applying methods of statistical physics to study crackles.
  • Study an apparent paradoxical behavior of the lung: during inflation from the collapsed state, the mammalian lung does not always develop an increasing restoring force; instead, the pressure inside the lung intermittently decreases.
  • Understand the dynamics of the amphiphilic molecules which compose the lung surfactant. Those molecules play a vital rule during breathing, small changes in they fraction may be deadly.



Main Publications
Dynamic Instabilities in the Inflating lung PDF file abstract
AM Alencar; S Arold; SV Buldyrev; A Majumdar; D. Stamenovic; HE Stanley; B Suki
Nature, 417, pp. 809-911, June 2002
Avalanche dynamics of crackle sound in the lung PDF file abstract
AM Alencar; SV Buldyrev; A Majumdar; HE Stanley; B Suki
Phys. Rev. Lett., 8708 (8), pp. 8101, AUG 2001
Life-support system benefits from noise PDF file
B Suki; AM Alencar; MK Sujeer; KR Lutchen; JJ Collins; JS Andrade; EP Ingenito; S Zapperi; HE Stanley
Nature, 393, pp. 127-128, MAY 1998
Self-organized percolationPDF file
AM Alencar; JS Andrade; LS Lucena
Phys. Rev. E, 56 (3), pp. 0-0, SEP 1997




Visitant Number:
Adriano Alencar
Last modified: Tue Dec 17 14:33:23 EST 2004