The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Kenneth E. Jesse - One of the best experts on this subject based on the ideXlab platform.
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Computer Simulation of Radioactive Decay
The Physics Teacher, 2003Co-Authors: Kenneth E. JesseAbstract:The straightforward way to determine the half-life of a radioactive substance is to measure its activity in each of a series of time intervals, plot the data as a function of the accumulated time on Semilog Paper, and then measure the slope of the graph. A computer simulation of this procedure follows based on material presented in Clifford E. Swartz's excellent book, Used Math.1 He presents a very fine mathematical derivation of the exponential law of decay for radioactive atoms in Chapter 4. A brief summary follows using his notation and equation numbers.
S. Ranganna - One of the best experts on this subject based on the ideXlab platform.
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Determination of a thermal process schedule for guava (Psidium guajava Linn.)
International Journal of Food Science and Technology, 2007Co-Authors: Nirankar Nath, S. RangannaAbstract:A thermal process schedule for guava canned in syrup was evolved on the basis of inactivation of pectinesterase (PE) which was found to be more heat resistant than peroxidase. Values for thermal inactivation and thermal resistance of PE in syrup homogenate containing guava pulp and sugar syrup in the ratio of 11:6 and total soluble solids content of 20% at pH 4.0 were F [29.22; 205.1] = 1.0 and D [29.81; 205.1] = 0.592, resp. The F value of 1 was equivalent to 1.69 D. In commercial canning, a 2.5 D process is recommended, which ensures a microbiologically safe and organoleptically acceptable product. Process time was calculated both by graphical and formula methods. Calculation by the formula method using slopes of heating and cooling curves plotted on Semilog Paper by least squares analysis, and fh/U:g [Sterilization in Food Technology (1957) by Ball + Olson, McGraw-Hill Book Co., New York] tables for actual values of jc gave process times very close to those obtained by the graphical method. Process times required at different initial and processing temp. are given. To minimize viscosity increase in the covering syrup during storage, firming of guava in 1% CaCl2 solutions for 30 min prior to canning is suggested. In addition, use of covering syrup containing 0.125% ascorbic acid with or without citric acid (0.06%) yields a product of good colour, texture and flavour.
Nirankar Nath - One of the best experts on this subject based on the ideXlab platform.
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Determination of a thermal process schedule for guava (Psidium guajava Linn.)
International Journal of Food Science and Technology, 2007Co-Authors: Nirankar Nath, S. RangannaAbstract:A thermal process schedule for guava canned in syrup was evolved on the basis of inactivation of pectinesterase (PE) which was found to be more heat resistant than peroxidase. Values for thermal inactivation and thermal resistance of PE in syrup homogenate containing guava pulp and sugar syrup in the ratio of 11:6 and total soluble solids content of 20% at pH 4.0 were F [29.22; 205.1] = 1.0 and D [29.81; 205.1] = 0.592, resp. The F value of 1 was equivalent to 1.69 D. In commercial canning, a 2.5 D process is recommended, which ensures a microbiologically safe and organoleptically acceptable product. Process time was calculated both by graphical and formula methods. Calculation by the formula method using slopes of heating and cooling curves plotted on Semilog Paper by least squares analysis, and fh/U:g [Sterilization in Food Technology (1957) by Ball + Olson, McGraw-Hill Book Co., New York] tables for actual values of jc gave process times very close to those obtained by the graphical method. Process times required at different initial and processing temp. are given. To minimize viscosity increase in the covering syrup during storage, firming of guava in 1% CaCl2 solutions for 30 min prior to canning is suggested. In addition, use of covering syrup containing 0.125% ascorbic acid with or without citric acid (0.06%) yields a product of good colour, texture and flavour.
Gong Jia-dong - One of the best experts on this subject based on the ideXlab platform.
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Analysis on Drainage Basin Characteristics of the Upper Reaches of Heihe River
Journal of Desert Research, 2020Co-Authors: Gong Jia-dongAbstract:Based on the Horton linear measures, this Paper analyzed drainage basin characteristics of the upper reaches of the Heihe river. The tributaries can be divided into 5 orders on the topographic map with the scale of 1:250 000. According to the measuring results, the drainage basin characteristics do not submit to the stream law absolutely. The law of stream numbers can be applicable in this area with higher bifurcation ratio, but the law of stream length does not be applicable. The relationship between the accumulative volume of the averaged stream length and stream order is linear in the Semilog Paper while the relationship between the total stream length and stream order in the log-log grid. The frequency and density of the stream are positive correlated to local climatic condition. The frequency and density under moist climate are higher than under drought climate while the stream flow is related to local precipitation. The sediment charge is positive correlated to stream dicing. In the north slope of the Qilian Mountain, the sediment of the river is mainly from transverse valleys.
Kenneth J. Pienta - One of the best experts on this subject based on the ideXlab platform.
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RATIONAL USE OF CHEMOTHERAPY: It Is Not Just Rat Poison
Urologic Clinics of North America, 1999Co-Authors: Jeffrey M. Kamradt, Eric A. Klein, Kenneth J. PientaAbstract:Several decades ago, Skipper and co-workers 6 , 7 laid the groundwork for the current understanding of tumor growth. The combined results and analysis of a large body of work with the rodent leukemia L1210 model were synthesized into the log-kill model. 6 , 7 L1210 leukemia is a rapidly growing tumor with a large percentage of cells actively synthesizing DNA, which allows the cells to have a predictable growth pattern. Skipper and colleagues found that the cells had an exponential growth pattern; when this was plotted on Semilog Paper, a straight line was obtained. The doubling time of the tumor was constant, that is, the amount of time needed for a tumor to grow from 10 to 100 cells equaled the amount of time needed to grow from 1000 to 2000 cells. Skipper and colleagues also found that the animals died when the cells reached a critical level (approximately 109). The relationship between tumor size and survival is graphically demonstrated in Figure 1 . Because L1210 leukemia follows a consistent growth pattern, the effect of chemotherapy can be extrapolated from the survival benefit the animals exhibit following therapy. For example, 1 an increase in survival of 2 days would be equivalent to a 90% reduction of tumor cells (a 1 log-kill) or a reduction from 105 to 104. A 99.999% destruction of tumor cells represents a 5 log-kill but would not cure the animal unless the initial inoculum (tumor burden) was small (less than 104). A corollary to this observation is that survival is a function of tumor size at initial treatment, that is, the smaller the tumor at the initiation of effective therapy, the greater the chance for cure (Fig. 1) . Skipper and colleagues demonstrated that cell kill by cytotoxic chemotherapy follows first-order kinetics. This theory is termed fractional cell kill. A given concentration of drug applied for a defined period of time will kill a constant fraction of the total cell population, independent of the absolute number of cells. Therefore, a single treatment with an effective drug will not be sufficient to eradicate a tumor. Treatment results will depend on both the dose of drug administered as well as the frequency of treatment. In order for the log-kill theory to apply to a particular tumor, that tumor must be growing exponentially. The L1210 leukemia model fits this requirement; however, most human tumors do not. Unfortunately, most human tumors are diagnosed when they are large and kinetically heterogeneous. These tumors follow a pattern of nonexponential growth first described by Gompertz. 3 Gompertzian growth exhibits a steadily increasing doubling time. This results in a S-shaped curve with an initial slow growth rate, followed by a linear middle portion and a later plateau phase (Fig. 2) . Small tumors will have the largest growth fraction; however, this large growth fraction will not lead to a large increase in tumor number given the small number of cells initially present. At the other extreme, large tumors will have many cells but exhibit a small growth fraction. In the middle portion of the curve, growth will be at a maximum because the number of proliferating cells will be largest. This maximum is achieved at about one-third of the maximum tumor volume. The gompertzian model has been applied to the natural history of human breast cancer and was found to explain the clinical observations seen following adjuvant therapy. 4 At the time of clinical detection, human solid tumors are already large enough that their growth of S-phase fraction is less than 10%. It is possible that the use of prostate-specific antigen (PSA) as a biochemical marker will allow the detection of prostate cancers much earlier. Patients with a rise in the PSA to 0.1 postprostatectomy may have tumors with a high growth fraction and be more amenable to cure than when their PSA reaches higher values. This is currently being tested in several clinical trials.
