Archive for September, 2007
What’s That I Hear: Domestic Surveillance and Counterintelligence on Antiwar Musicians in the 1960s
During the 1960′s era, the Federal Bureau of Investigation (FBI) engaged in numerous campaigns of intelligence gathering and counterintelligence against an unknown number of targets that were perceived as threats to the American government. Among these targets were numerous musicians who chose to voice protest against U.S. involvement in Vietnam through song. My paper examines the FBI’s surveillance and counterintelligence activities carried out against these musicians, most notably folksinger Phil Ochs, and questions whether such efforts were necessary for maintaining national security, or were instead an attempt to compel a more favorable environment for war-making. Looking further, I question whether similar actions could be carried out in today’s comparably polarized wartime environment, and what might be done to help protect the voice of peace from an often hostile government.
Fluid-Structure Analysis of Cellular Deformation and Detachment during Airway Reopening
Pathological conditions such as pneumonia and sepsis can lead to acute respiratory distress syndrome (ARDS), a condition characterized by fluid accumulation in the distal airways. Ventilation of ARDS patients produces microbubbles which reopen fluid-occluded airways and may deform, injure and/or detach epithelial cells (EpC) from the airway wall. Although in-vitro systems can mimic airway reopening conditions, current visualization techniques cannot quantify cell deformation and detachment during microbubble flows. To investigate these processes we developed 3D finite element models of EpC under airway reopening conditions. These models utilized in-vitro confocal microscopy to specify cellular morphology and optical tweezer measurements to specify the EpCs viscoelastic properties. Boundary element solutions were used to specify hydrodynamic loading on the EpC and adhesion properties were based on a steered molecular dynamic (SMD) simulation of the integrin-collagen complex. We also developed a hybrid boundary element/finite element method to investigate the effect of cell deformability on the hydrodynamic stresses generated by the air-liquid interface. Results indicate that both cytoskeletal and membrane mechanical properties can influence the risk of injury and detachment. These results have helped explain counter-intuitive experimental data and may lead to the development of improved treatments for ARDS
Hannah L. Dailey is a NSF Graduate Research Fellow and Samir N. Ghadiali is a Parker B. Francis Fellow in Pulmonary Research.
Design of unidirectional subwavelength slit coupler for THz surface plasmons
In this paper, we demonstrate a unidirectional subwavelength slit coupler at THz frequencies by using two-dimensional finite difference time domain (FDTD) modeling. The near-field light emitted from the narrow slit serves as a subwavelength-scaled excitation source. By placing a particular grating structure on one side of the slit, the light could be guided in only one direction. This unidirectional subwavelength slit coupler is amenable to incorporation into optical integrated circuits at THz frequencies.
Simulation of Derivative Characteristics of Broadband Quantum Dot Lasers
We present the development of theoretical model based on multi-population rate equation to assess the derivative optical gain and chirp characteristics from the multiple states broadband InGaAs/GaAs quantum-dots laser. Our results show that the linewidth enhancement factor from the ground state is slightly larger but in the same order of magnitude as the values obtained in conventional quantum-dot lasers. This study is important in proving the competency of this novel device for diverse applications.
Document Content Inventory and Retrieval
We give an analysis of relationships between expected retrieval performance and classication recognition accuracy in the context of document image content extraction and inventory. By content extraction we mean location and measurement of regions containing handwriting, machine-printed text, photographs, blank space, etc, in documents represented as bilevel, grey-level, or color images. Recent experiments have shown that even modest per-pixel content classication accuracies can support usefully high recall and precision rates (of, e.g., 8090%) for retrieval queries within document collections seeking pages that contain a given minimum fraction of a certain type of content. In an effort to elucidate this interesting empirical result, we have analyzed the interdependency of classication and retrieval under a variety of assumptions about the distribution of content types in document image collections. We show that under general conditions we cannot derive precision and recall measures from per-pixel classication measures alone, but we can estimate the expected values of these measures. If however the distribution of content and error rates are uniform across the entire collection, our results suggest, it is possible to predict precision and recall measures from classication accuracy and vice versa. historical documents; rectilinear and complex non-rectilinear layouts; and clean and degraded images.