We are interested in finding the regions where the trans-illumination diagnostic beam indicates some kind of change and interpret it potentially as anomaly. Upon simulation we found that the trans-illuminated signal may be measured on axis even when the sample is too thick (dμs=10) to permit trans-illumination with ballistic photons. Assuming a single scattering case, corresponding to a weakly scattering sample that is in the literature simulated as a flesh of a chicken breast, we find that even a small aperture transmits signal that may be used to identify sample differentiation. We show the spreading of the trans-illuminated signal that clearly depends on the depth of anomaly, allowing determination of its position. Upon scanning of the probe beam, changes in transillumination delineate the transverse extend of the anomaly. Our simulations agree with published results.
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.
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.
DNA sequences in human genome can be divided into the coding and noncoding ones. We hypothesize that the characteristic periodicities of the noncoding sequences are related to their function. We describe the procedure to identify these characteristic periodicities using the wavelet analysis. Our results show that three groups of noncoding sequences, each one with different biological function, may be differentiated by their wavelet coefficients within specific frequency range.
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
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.
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.
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.
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.
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.
We review the evolution of machine vision and comment on the cross-fertilization from the neural sciences onto flourishing fields of neural processing, parallel processing, and associative memory in optical sciences and computing. Then we examine how the intensive efforts in mapping the human brain have been influenced by concepts in computer sciences, control theory, and electronic circuits. We discuss two neural paths that employ the input from the vision sense to determine the navigational options and object recognition. They are ventral temporal pathway for object recognition (what?) and dorsal parietal pathway for navigation (where?), respectively. We describe the reflexive and conscious decision centers in cerebral cortex involved with visual attention and gaze control. Interestingly, these require return path though the midbrain for ocular muscle control. We find that the cognitive psychologists currently study human brain employing low-spatial-resolution fMRI with temporal response on the order of a second. In recent years, the life scientists have concentrated on insect brains to study neural processes. We discuss how reflexive and conscious gaze-control decisions are made in the frontal eye field and inferior parietal lobe, constituting the fronto-parietal attention network. We note that ethical and experiential learnings impact our conscious decisions.
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.
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.
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