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The Physics of Human Thermography
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
Radiative heat transfer occurs via infrared waves traveling between two separate objects, which may be at different temperatures. This transfer can occur even through a vacuum. Bodies receive radiated electromagnetic energy emitted by the surroundings, some of which is reflected and the remainder absorbed. Whereas emissions of radiant energy entail a decrease in internal energy, absorption results in an increase. Radiance is a directional (vector) quantity. Therefore, if a body maintains a constant temperature it is in thermal equilibrium; the energy emitted is counterbalanced by the energy absorbed plus any heat energy produced internally. If a body is at either a higher or lower temperature than its surroundings, the net radiative heat transfer is the difference between emitted and absorbed radiation. In infrared imaging, this radiative heat transfer occurs simultaneously between the human subject and the local environment, of which the thermal imager itself is an integral part. The sum of the infrared radiation emitted and reflected from a surface is what a radiometric thermal imager detects and quantifies as surface temperature. About 60% of the heat lost by the human body is lost through radiation.
Noninvasive Sensing of Serum sRAGE and Glycated Hemoglobin by Skin UV-Induced Fluorescence
Published in Andrey V. Dunaev, Valery V. Tuchin, Biomedical Photonics for Diabetes Research, 2023
Vladimir V. Salmin, Tatyana E. Taranushenko, Natalya G. Kiseleva, Alla B. Salmina
Another example is the medical spectrometer analyzing both fluorescence and reflection spectra known as “Skin-AGE” [40]. The device is based on local spectroscopy assessing with the fiber multichannel spectrometer. To excite fluorescence, radiation with a wavelength of 365 nm is used. Fluorescence spectra are measured in radiometric mode and recorded in units of the spectral power density of the radiation. Examination can be taken on various areas of the skin (fingertips, palms, wrist, shoulder, forearm, elbows, knee, lower leg, and ankle). The analyzer has been used in patients with diabetes mellitus. Experimental models of “Skin-AGE” spectrometers with external and built-in computers have been created [41].
Remote Sensing and Computational Epidemiology
Published in Abbas Rajabifard, Greg Foliente, Daniel Paez, COVID-19 Pandemic, Geospatial Information, and Community Resilience, 2021
Geo-referencing, Radiometric calibration (Atmospheric corrections), and DN to radiance and then reflectance conversion for the visible and SWIR and DN to radiance for thermal bands were the processing steps that were taken. These images were used for producing the following products.
Evaluating the blue-light hazard from solid state lighting
Published in International Journal of Occupational Safety and Ergonomics, 2019
John D. Bullough, Andrew Bierman, Mark S. Rea
The physical characteristics of the eye, including its approximately spherical shape, a round pupil opening formed by the iris and an adjustable lens, enable it to function as a precise imaging device. Light incident on the pupil opening is focused on the retina, where it forms an irradiance distribution corresponding to the radiance of the scene outside the eye. Using geometrical optics and radiometry principles, and ignoring absorption and scattering in the eye for the moment, the following equation can be derived [54]: Eretina= retinal irradiance; L= radiance being focused; Apupil= area of the pupil opening; feye= focal length of the eye, roughly 1.7 cm. As stated previously, Eretina is the irradiance at a point on the retina, not an average, and the corresponding radiance is for a specific viewing direction which, e.g., can be a small light source in the field of view.
DNA electromagnetic properties and interactions -An investigation on intrinsic bioelectromagnetism within DNA
Published in Electromagnetic Biology and Medicine, 2018
Masroor Hassan Bukhari, Salma Batool, Dr Yasir Raza, Omar Bagasra, Abbas Rizvi, Asifa Shah, Tashmeem Razzaki, Tipu Sultan
Our experiments comprised two major strategies, first, to measure the sample’s intrinsic electromagnetic response using an antenna in the proximity methodology, similar to RF radiometry, and second, using a direct-contact antenna method, similar to the electrometry methods. Suitable experiments for each method were carefully designed. The first suite of experiments (Figure 1) comprised a special micro-mesh copper coil antenna we devised for the purpose of measuring low to high frequency fields within the DNA. The antenna was developed using a mesh of 32SWG 99.99% pure copper wire, covering the entire surface area of the vial, and the two ends were joined together to convey the signal. The signal obtained from the antenna was amplified with the help of a custom-made ultra-sensitive ultra-low-noise RF pico-ampere Trans-Impedance Amplifier (TIA), based on the femto-ampere input LMC6622 chip (National Semiconductors Corp., Santa Clara, CA.), operated with a regulated power supply based on batteries. The amplifier was calibrated with a 2182A Nano-volt Digital Multimeter with a precision source (Keithley Corp., Solon, OH.). The second suite of experiments (Figure 2), was quite similar to the first, with the exception that the coil antenna was replaced by a copper electrode antenna, which had a direct contact with genetic material kept in a petri dish. The output of the antenna was read using the same procedure with our TIA as with the first suite of experiments.
The use of infrared thermography in the measurement and characterization of brown adipose tissue activation
Published in Temperature, 2018
James Law, Jane Chalmers, David E. Morris, Lindsay Robinson, Helen Budge, Michael E. Symonds
IRT is the process of constructing an image of an object's temperature by first measuring the IR radiation being emitted, then converting that radiometric data to a temperature and, finally, displaying the temperature data as an image. The IR radiation emitted is related to the temperature of the body with long-wavelength IR (8–15μm) emitted by objects whose temperature is between -80°C and 89°C, including the human body.68 Planck's Law can be used to convert radiometric data to temperature data when accounting for emissivity of the body being measured.68,69 In addition, adjustment must be made for any attenuation of the signal prior to it reaching the detector, for instance due to water vapor in the atmosphere (a function of humidity and distance).68 The variables used in the conversion are listed in Table 1 along with an outline of their effect.