Michelle K. Scholl

Interferometric Tissue Characterization: I: Theory

We describe a new method of determining path-integrated tissue density using a modified interferometric scattering experiment. The method is based on the ability of the photons, passing through the sample without scattering (or absorption) to preserve their coherence (polarization and phase). We present the theory that predicts the feasibility of this method. The highest value of fringe incidance contains the information about the sample transmission.

Extrasolar planet observatory on the far side of the moon

Abstract We define the simplest signal-to-noise ratio (SNR) to determine the optimal wavelength interval for extrasolar planet detection. We expand the width of the spectral region from infrared up to submillimeter range. For a nearby solar system similar to our own, we find that the SNR increases by about 100 in comparison to that considered previously. We propose the planet detection in a spectral interval around 0.3 mm (900 GHz), in which we evaluate the SNR to be 10 – 4 . We perform trade-off analysis for alternative sites for the planet observatory, concluding that the far side of the moon offers a most favorable, atmosphere-free environment and a stable base.

Black-body radiation, emissivity, and absorptivity

We review theoretical considerations that give rise to the blackbody radiation inside a cavity with completely absorbing walls at a specific temperature. We examine the applicability of this model to the experimentally observed properties of radiation sources. We assess relevance of emissivity and its far-reaching implications. We examine its changing nature and measurement challenges

Ballistic photons in tissue characterization study

We describe a new method to separate ballistic from the scattered photons in a tissue characterization study. It is based on the concept that the scattered photons acquire a phase delay whose magnitude depends on the number of scatterings and the resulting path increment for photons transmitted in the direction of incidence. All other photons are eliminated with physical apertures in his scanning arrangement. We propose a Mach-Zehnder experimental setup where the ballistic photons pass through the sample with the delay caused uniquely by the sample indices of refraction, assuming multiple layers. The method is based on the capability of the photons, passing through the sample without scattering or absorption to preserve their coherence. With the incorporation of a movable mirror on the piezoelectric actuator in the reference arm, this method allows measuring only those photons that suffer no phase delay upon passing through the sample. We present the theory that predicts the feasibility of this method to differentiate between classes of tissues. The method is feasible for samples with transmission of ballistic photons down to 10-18.

Engineering intelligent structures for energy efficiency

The current philosophy of designing intelligent buildings emphasizes the use of materials whose performance is compatible with thermal environment that changes daily and seasonally. Ideally, engineering designs should incorporate features to reflect as much energy as feasible and store excess thermal energy. This may be for usage during periods when thermal energy is needed for heating. We show that current construction design methods may be improved for energy efficiency, by incorporating an attic as an transitional space for energy storage during summer, and by employing roof materials with high reflectivity in the visible and in the near IR (up to about 1.9 μm). Thus, traditional red or pink brick roofs, potentially glazed or covered with low reflectivity coating, would likely remain (become again) the preferred construction material.

Thermal pulse propagation in the search of subcutaneous masses

We examine the mechanisms of pulse propagation inside tissue to determine the spectral intervals wherein the pulse might propagate to an occlusion and reflect from its boundary. We derive analytical expression, showing that the depth of occlusion may be determined upon measuring the time during which the input temperature pulse travels to the inclusion, is reflected from it, and returns to the front of the skin surface. Additionally, we derive the speed of pulse propagation from diffusivity and material time constants. These quantities are calculated from the published tissue parameters; they could also be calibrated for specific classes of the biological samples. For breast tissue monitoring, we propose to use near IR laser pulses.

Noncoding sequence classification based on wavelet transform analysis: part II

DNA sequences in human genome can be divided into the coding and noncoding ones. Coding sequences are those that are read during the transcription. The identification of coding sequences has been widely reported in literature due to its much-studied periodicity. Noncoding sequences represent the majority of the human genome. They play an important role in gene regulation and differentiation among the cells. However, noncoding sequences do not exhibit periodicities that correlate to their functions. The ENCODE (Encyclopedia of DNA elements) and Epigenomic Roadmap Project projects have cataloged the human noncoding sequences into specific functions. We study characteristics of noncoding sequences with wavelet analysis of genomic signals.

Propagation dynamics of a mountain fire: case of the Yarnell Hill Fire 2

We propose a novel model for the fire evolution, applicable to its spread in mountains, with low-height fuel. Fire propagates along contours of equal elevation on steep terrains. The wind outside the mountain does not conserve on the inside slopes at fuel height. The local wind depends on micro-climatic environment, influenced additionally by the fire itself.

Analysis of propagation of complex fire: case of the Yarnell Hill Fire 1

We examine the propagation of the Yarnell Hill Fire in Arizona, June 28 -- July 3, 2013 to assess the nature of its complexity. We identify the critical fire growth that starts about 35 hours after the fire initiation. In a time span of three hours, the fire area is doubled. Within the following four hours, the direction of fire turns by about 180 degrees. An hour later, a pyrocumulonimbus cloud is observed above the fire area. To monitor complex fires, we propose implementation of an IR instrument to scrutinize fire remotely for behaviors, such as vortices and rotation, arising from combustion events, terrain characteristics, and outside influences. We propose a small reconnaissance plane circling to the side and above the fire area to search for anomalies in fire propagation and atmosphere during the fire consolidation during the initial 45 hours. Ideally, the observing instrument would be sensitive in IR region at about 4.5 microns where carbon oxide emits and water transmits the radiation.

Optical Sciences Center at the University of Arizona in the late seventies: times of consolidation

On the occasion of the 50th anniversary of the founding of the Optical Sciences Center, we recall the times when this event took place. We review historical conditions both in Arizona and in science evolution at the University of Arizona and in the USA. We concentrate on the period when Professor Franken was the director of the center. His objective was to consolidate the Center and align it closely with the University standards and procedures. The fact that within the past decade this entity has become a University of Arizona College bears witness to the fact that Dr. Franken succeeded in this task.