Gamma ratio

The gamma dose rates given in Table I indicate higher readings on the phantoms, which is caused by neutron capture in the phantom. The gamma dose rates are reduced behind the iron and concrete shields by factor of 13 and 8, respectively. The neutron-to-gamma ratio varies from 12 for the bare and concrete shield to 60 for the steel shield. These values are higher than those usually quoted for similar assemblies because the neutron dose rate in this study are in units of mrem rather than mrad. A quality factor of between 8 and 9 applies for this assembly. ... 

Another method of polarizing nuclear spins is dynamic nuclear polarization (DNP), whereby the comparably large electron spin polarization (see Fig. 1) is transferred to nuclear spins by saturating the electron resonance. DNP is almost as old as NMR spectroscopy, building on the aforementioned theoretical work by Overhauser [21] who predicted what is today known as the Overhauser effect (OE). DNP was soon after demonstrated experimentally by Carver and Slichter [22, 23]. The enhancement, s, that can be obtained by DNP is determined by the gamma ratio 7e/7n> which is 660 for protons and 2,625 for... 

Due to the conversion process an absorbed photon give rise to less than one electron generated in the CCD. This phenomenon, also called a "quantum sink" shows that the detector is degrading the S/N ratio of the image. The quality of an image being mainly limited by the quantum noise of the absorbed gamma this effect is very important. 

Both side-chain and main-chain scission products are observed when polyacrylates are irradiated with gamma radiation (60). The nature of the alkyl side group affects the observed ratio of these two processes (61,62). 

Distribution models are curvefits of empirical RTDs. The Gaussian distribution is a one-parameter function based on the statistical rule with that name. The Erlang and gamma models are based on the concept of the multistage CSTR. RTD curves often can be well fitted by ratios of polynomials of the time. 

Several different mechanisms, most importtuitly alplia particle, beta particle, and gamma ray emissions accomplish radioactive transformations. Each of these mechanisms is a spontaneous nuclear transformation. Tlie result of tliese transformations is the formation of different stable elements. Tlie kind of transformation that will ttike place for any given radioactive element is a function of the type of nuclear inslabilitv as well as the mass/energy relationship. The nuclear instability is dependent on the ratio of neutrons to... 

Similar to beta decay is positron emission, where tlie parent emits a positively cliargcd electron. Positron emission is commonly called betapositive decay. Tliis decay scheme occurs when tlie neutron to proton ratio is too low and alpha emission is not energetically possible. Tlie positively charged electron, or positron, will travel at higli speeds until it interacts with an electron. Upon contact, each of tlie particles will disappear and two gamma rays will... 

ALT, alanine aminotransferase AST, aspartate aminotransferase GGT, gamma-glutamyl transferase INR, international normalized ratio LDH, lactate dehydrogenase PT, prothrombin time. 

Internal Conversion—Process in which a gamma ray knocks an electron out of the same atom from which the gamma ray was emitted. The ratio of the number of internal conversion electrons to the number of gamma quanta emitted in the de-excitation of the nucleus is called the "conversion ratio."... 

Relative Biological Effectiveness (RBE)—The RBE is a factor used to compare the biological effectiveness of absorbed radiation doses (i.e., rad) due to different types of ionizing radiation. More specifically, it is the experimentally determined ratio of an absorbed dose of a radiation in question to the absorbed dose of a reference radiation (typically 60Co gamma rays or 200 keV x rays) required to produce an identical biological effect in a particular experimental organism or tissue (see Quality Factor). 

RBE is used to denote the experimentally determined ratio of the absorbed dose from one radiation type to the absorbed dose of a reference radiation required to produce an identical biologic effect under the same conditions. Gamma rays from cobalt-60 and 200-250 keV x-rays have been used as reference standards. The term RBE has been widely used in experimental radiobiology, and the term quality factor used in calculations of dose equivalents for radiation safety purposes (ICRP 1977 NCRP 1971 UNSCEAR 1982). RBE applies only to a specific biological end point, in a specific exposure, under specific conditions to a specific species. There are no generally accepted values of RBE. 

Thompson SD, Luyrink LK, Graham TB, et al. Chemokine receptor CCR4 on CD4+ T cells in juvenile rheumatoid arthritis synovial fluid defines a subset of cells with increased IL-4 IFN-gamma mRNA ratios. J Immunol 2001 166(11) 6899-6906. 

Colombo, P. et al., J. Polymer Sci., 1963, Bl(8), 435-436 Mixtures containing ratios of about 20 1 and 12 1 of ethylene haloalkene undergoing polymerisation under gamma irradiation at 308 krad/h exploded violently after a total dose of 50 krad. Dose rate and haloalkene cone, were both involved in the initiation process. 

Procedures for curve fitting by polynomials are widely available. Bell shaped curves usually are fitted better and with fewer constants by ratios of polynomials. Problem P5.02.02 compares a Gamma fit with those of other equations, of which a log normal plot is the best. In figuring chemical conversion, fit of the data at low values of Ett) need not be highly accurate since those regions do not affect the overall result very much. 

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