Cumulative activity

A mixture of Me3210PbCl and 210Pb(NO3)2 was used to study the rate of ionic trimethyl-lead uptake by exposed plant surfaces. More specifically, the mean cumulative activity of the lead toxicants transferred across tomato cuticle was measured daily over a six-day period. Reversed-phase HPLC was used to separate and identify the lead species crossing the plant cuticle. It was found that appreciably more trimethyllead(I) (75% of the theoretical) than inorganic lead(II) (39%) was transferred. The apparent rate constants derived from the first-order plot of time in days versus the difference in observed activity were 0.0788 and 0.0346 day-1 for transfer of the trimethyllead(I) and inorganic lead(II), respectively. 

The Rb-81/Kr-81m generator can be used as an example. Experience has shown that a large field of view (LFOV) gamma camera equipped with a high resolution collimator requires the cumulative activities for the three typical procedures summarized in Table II. Solving equation (15) by succesive... 

Table II. Cumulative Activity Values of Kr-81m Required for Typical Nuclear Medicine Procedures...

Bolus Injection. The bolus mode consists of the successive perfusions of as many bolus (n) volumes as necessary to reach the cumulative activity required by the scintigraphic examination. A mathematical analysis of this technique results in the following equation ... 

The extent of CPO immobilized on the sol-gel was determined by the difference between the activity of the initial enzyme solution and that measured in cumulative washes. Based on the cumulative activity lost in six washes, a second preparation of the CPO-bound sol-gel contained 10, 24, and 55 mg of CPO/g of sol-gel for the 50-, 150-, and 200-A CPO sol-gels, respectively. In prior experiments, the total activity was measured and an estimated 80% of the bound CPO was active. The sol-gel immobilization is expected to limit the unfolding of the protein bound inside pores of the sol-gel. Thus, immobilization is expected to affect solvent stability and thermostability. Immobilization would probably not impact peroxide stability, since the mechanism of peroxide inactivation is associated with changes in the redox properties and oxidation state of the heme iron and the active center, which cannot be protected by immobilization. Experimental studies of immobilized CPO were therefore limited to temperature and solvent stability. 

Fall of container with spent nuclear fuel Assembly destruction with cumulative activity escape of gas products and iodine isotopes. 

Electrophilic cleavage of pentachlorophenylpentafluorophenylmercury provides a useful direct competition between pentafluorophenyl and pentachlorophenyl, for electrophilic attack. Exclusive attack at pentafluorophenyl occurs, showing that the cumulative activating effect of the ortho- and the para-fluorine substituents is dominant [168] (Figure 9.70). 

The cumulative activation for any node contains the activation received directly from the input layer as well as the intra-set acti-... 

FIG. 13.14. Initial clinical trials with Y-DOTATATE in Poland, patient No. 1 Treatment using four doses of Y-DOTATATE with a cumulative activity of 14.6 GBq. 

Figure 13.14 shows initial clinical trials of °Y-DOTATATE in patient No. 1, who was treated with four doses of Y-DOTATATE, using a cumulative activity of 14.6 GBq. The images show that liver deposits dominate the lesion with a high uptake of radiotracer. Tlie bremsstrahlung images after the four courses of therapy show significant decreases of uptake with each treatment session. 

Administer 82Rb by the infusion pump at the peak stress of the same cumulative activity as for the rest scan in Step 9. 

For a patient study, the patient gets an IV catheter that is connected to the patient line of the infusion pump. The desired total volume, total activity to be administered and the flow rate are all set on the console by the operator prior to the start of infusion. First, the low activity volume of saline as detected by the detector is flushed out to the waste bottle by applying the purge button. After purging, when the preset dose rate threshold is achieved as detected by the detector, the activity is directed to the patient line, and the set amount of the cumulated activity is administered. The pump stops after the infusion of the desired amount of activity, and all relevant parameters are printed out by the printer. 

When administered as a major amount concentrates in the thyroid gland, although to a lesser extent in differentiated thyroid cancer compared with normal thyroid tissue. The short range of the emitted beta particles leads to cell damage and cell death. The emitted radiation, however, can be harmful to other organs of the patient and has the potential to induce cancer, especially with repeated treatments and high cumulative activities. Other people in the vicinity of the patient may be exposed to external radiation and contamination. For children, thyroid cancer after radiation exposure appears to be a significant risk, as has been documented after the accident in Chernobyl. 

A significantly increased risk of second primary cancers and leukemia has been reported with high cumulative activities of (>22GBq). 

In the above-mentioned studies, the risk of a second malignancy after treatment with l is small. The risk, however, increases with high cumulative activities, especially when exceeding 18.5—22GBq, as pointed out in the European consensus statement (Pacini et al., 2006). 

For a dicussion of the effectiveness of deconvolution approaches in finding the most active component and problems with cumulative activity see Freier el al. 480-482... 

Snyder WS. Absorbed Dose Per Unit Cumulated Activity for Selected Radionuclides and Organs, Nm/mird Pamphlet No.ll. Oak Ridge Oak Ridge National Laboratory 1975. 

Some combinatorial synthetic approaches rely on the synthesis and testing of mixtures to achieve high throughput. Typically, one wants to maximize the diversity of each pool, so the activity of a pool is indicative of the activity of its most potent compound. However, when sensitivity of the test or solubility of the compounds has been a problem, some groups have, instead, pooled similar compounds, amplifying a weak signal by the epitope effect, that is, the cumulative activity of many related compounds. Regardless of whether compounds are pooled, the methods described previously allow one to maximize either the similarity or diversity of the pools. 

Considering these parameters, the learning process itself can be described to be cumulative, active, goal-oriented, and constructive [51, 52]. 

In the MIRD formalism, the mean absorbed dose to a target region from uniformly distributed, cumulative activity in the source region r/, becomes the following ... 

The reduction algorithm sums the sorted activity indices until the Cumulative Activity Index (CAl) exceeds the user-specified threshold. The summation process starts with the element that is considered the most important (rO and the cumulative activity index is set to be equal to the activity index of element r. Then, the next important element (r2) is added and the cumulative activity index is increased by the addition of the activity index of r2 to the previous cumulative activity index. For a given number of included elements, i, the cumulative index is given by... 

This procedure is repeated until the cumulative activity index exceeds the specified threshold (P) as shown in Fig. 2.4. The elements that have been accounted for in the cumulative activity index are the significant elements and, therefore, are the only elements included in the reduced model. The remaining elements of the full... 

Rank element name Activity [J] Activity index [%] Cumulative activity index [%]... 

Synder WS, Ford MR, Warner GC, Waston SB. Absorbed dose per unit cumulated activity for selected radionuclides and organs., in MIRD Pamphlet Number 11. New York, NY Society of Nuclear Medicine, 1975-1976... 

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