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A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror .
The concept of addressed fiber Bragg structures was introduced in 2018 by Airat Sakhabutdinov [1] and developed in collaboration with his scientific adviser, Oleg Morozov. . The idea emerged from the earlier works of Morozov and his colleagues, [2] [3] where the double-frequency optical radiation from an electro-optic modulator was used for the definition of the FBG central wavelength based on ...
Time-resolved simulation of a pulse reflecting from a Bragg mirror. A distributed Bragg reflector (DBR) is a reflector used in waveguides, such as optical fibers.It is a structure formed from multiple layers of alternating materials with different refractive index, or by periodic variation of some characteristic (such as height) of a dielectric waveguide, resulting in periodic variation in the ...
The HNRCA is one of the largest research centers in the world studying nutrition and physical activity in healthy and active aging and the prevention of age-related disease. [5] It has made significant contributions to U.S. and international nutritional and physical activity recommendations, public policy, and clinical healthcare. [6]
The metabolic stability theory of aging suggests it is the cells ability to maintain stable concentration of ROS which is the primary determinant of lifespan. [37] This theory criticizes the free radical theory because it ignores that ROS are specific signalling molecules which are necessary for maintaining normal cell functions. [37]
The 31-member Research Advisory Board of de Grey's SENS Research Foundation have signed an endorsement of the plausibility of the SENS approach. [48] In 2021, the National Institute on Aging (NIA), a division of the U.S. National Institutes of Health (NIH), showcased a SENS research project and provided a grant for the research. [49] [50]
Accelerated aging is testing that uses aggravated conditions of heat, humidity, oxygen, sunlight, vibration, etc. to speed up the normal aging processes of items. It is used to help determine the long-term effects of expected levels of stress within a shorter time, usually in a laboratory by controlled standard test methods .
The theory that DNA damage is the primary cause of aging is based, in part, on evidence in human and mouse that inherited deficiencies in DNA repair genes often cause accelerated aging. [ 29 ] [ 30 ] [ 27 ] There is also substantial evidence that DNA damage accumulates with age in mammalian tissues, such as those of the brain, muscle, liver and ...