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Multispectral Image Segmentation in Magnetic Resonance Imaging
Published in Edward R. Dougherty, Digital Image Processing Methods, 2020
Joseph R. Hornak, Lynn M. Fletcher
The proportionality constant γ is called the gyromagnetic ratio. The gyromagnetic ratio is a function of the magnitude of the nuclear magnetic moment. Each isotope with a net nuclear spin possesses a unique γ. Three of the most abundant spin-bearing nuclei found in the human body are hydrogen, 1H; sodium, 23Na; and phosphorus, 3IP (Table 1). The magnetic field experienced by a nucleus is altered by the electron cloud around it. As a consequence, the resonant frequency of a nucleus is dependent on the chemical compound with which the nucleus is associated. The variation in ν from chemical compound to compound is on the order of parts per million of ν and is called chemical shift. A 3IP NMR spectrum of muscle tissue will possess five absorptions due to the five types of phosphorus: inorganic phosphate, phosphor creatine, and α, β, and γ adenosine triphosphate.
Muscular work
Published in Karl H.E. Kroemer, Fitting the Human, 2017
Thousands of individual muscle fibers run in bundles, essentially parallel, along the length of the muscle. Inside the bundles are hundreds of mitochondria. They are the muscle’s power factories, cells specialized to liberate chemically stored energy (in ATP, adenosine triphosphate, and CP, creatine phosphate°). That energy enables the muscle to contract. Blood supply is essential for muscle function because it supplies energy and oxygen and removes the by-products of metabolic processes (see Chapter 10) such as heat, water, and carbon dioxide. Nervous signals trigger the actions of the muscle and control their intensity. Contractile microstructure
Biological Correlates of Microwave
Published in Jitendra Behari, Radio Frequency and Microwave Effects on Biological Tissues, 2019
Lerchl et al. (2008) have shown that chronic RF exposure (383 MHz, 900 MHz, and 1800 MHz) leads to frequency-dependent increase of body weight in Djungarian hamsters at moderate SAR values. These authors have concluded that this is indicative of metabolic processes may be affected by such exposures. It is possible that molecular processes involved with the brain energy metabolism of the rat may be perturbed by the radiation in the microwave frequency region. It has been reported that there are divalent iron atoms and two divalent copper atoms in the molecules of the respiratory chain (Lehninger 1965). Each of these is essential to the function of the respiratory at the molecular level. Charged particles in an electric field undergo translational motion if not otherwise constrained. Such a group of particles would possibly respond to the oscillating electric field having wide range starting from radiofrequency oscillation to the highest value that is limited by natural process to react (Sanders et al. 1984). Nicotinamide adenine dinucleotide (NADH), biochemical assay for adenosine triphosphate (ATP), and creatine phosphate (CP) are key compounds in brain energy metabolism. ATP is a key compound in energy metabolism because it is the carrier of energy to the processes in living cells. NADH oxidized produces ATP in the mitochondria, while brain ATP concentration is maintained at the expense of CP. When demand for ATP is higher than the mitochondrial production capacity, CP is rapidly converted to ATP to sustain its level and significant decrease in CP levels is observed prior to any decrease in ATP. The changes in these compounds are frequency dependent.
Dietary supplements for consideration in elite female footballers
Published in European Journal of Sport Science, 2022
Hannah C. Sheridan, Lloyd J. F. Parker, Kelly M. Hammond
Some research has linked creatine supplementation with negative side effects. However, a recent meta-analysis found that there are no adverse, renal or hepatic consequences of creatine supplementation in females (de Guingand, Palmer, Snow, Davies-Tuck, & Ellery, 2020). Weight gain is often seen as a side effect of creatine. Although de Guingand et al. (2020) report no significant change in body weight in females supplementing with creatine, at an individual level some participants did report a small weight increase, which for some players may be undesirable.