Intrinsic controls

These are made of boron carbide ia a matrix of aluminum oxide clad with Zircaloy. As the uranium is depleted, ie, burned up, the boron is also burned up to maintain the chain reaction. This is another intrinsic control feature. The chemical shim and burnable poison controls reduce the number of control rods needed and provide more uniform power distributions. 

Meyer, G. A., Wells, S. G., and Jull, A. J. T. (1995). Fire and alluvial chronology in Yellowstone National Park Climatic and intrinsic controls on Holocene geomorphic processes. Geol. Soc. Am. Bull. 107, 1211-1230. 

McMahon The subject hasn t arisen in our discussion, but we should mention homeobox (Hox) genes here. The current model of the profound role that these play is that they regulate sizes and structures. It is a powerful argument that the reason that our radius and ulna are a different size from our humerus is because of the Hox genes that somehow intrinsically control that system. In the absence of the Hox genes, what you get is the formation of the initial anlages but a failure of growth of those structures. 

Intrinsic control mechanisms ensure that the cycle is executed completely, so that, following cell division, both daughter cells are equipped with the same genetic information as far as possible. Of the many control mechanisms, the following are highlighted ... 

A cell that has suffered DNA damage can bring about a halt in the cell cycle with the help of intrinsic control mechanisms (DNA damage checkpoints, see 13.7). The aim is... 

Use of Hormones to Alter Normal Endocrine Function. Because of the intrinsic control mechanisms in the endocrine system, administration of exogenous hormones can often affect the normal release of hormones. This fact can be exploited in certain situations to cause a desired change in normal endocrine function. For instance, oral contraceptives containing estrogen and progesterone inhibit ovulation by inhibiting the release of LH and FSH from the anterior pituitary. 

Internal controls, also known as built-in or intrinsic controls, contain the target antigen within normal tissue elements, in addition to the tissue elements to be evaluated. Thus, they can replace external positive controls. This is ideal, as the tissue elements to be evaluated... 

Ultrastructural characterization of the D2 receptors have revealed that they are often present within the GABA-containing cells within the striatum, cerebral cortex, hippocampus, globus pallidus and thalamic reticular nucleus (Mrzljak et al., 1996). Thus, dopaminergic transmission via the D2 receptors predominantly provides inhibitory local intrinsic control in the cerebral cortex and inhibitory regulation of the projection pathways. 

Most flavourings are complex mixtures of many compounds. As IRMS makes only sense with pure analytes, a strict purification of individual substances is indispensable. Therefore GC-IRMS has been further developed and optimised to multi-compound isotope ratio analysis by its coupling IRMS to capillary (c) and multidimensional (MD) gas chromatography (see 6.2.2.2.2). This methodology demands a strict intrinsic control and standardisation [340] apart from the international standards (see Table 6.3) also secondary standards like the polyethylene foil IAEA-CH7 or the NBS22 oil are available from the IAEA in Vieima. However, as these substances are also not suitable for the direct standardisation of data from a coupled GC system for flavour isotope analysis, certificated tertiary laboratory standards for hydrogen have been developed by parallel analysis of flavour compounds by TC/EA-IRMS and MDGC-P-IRMS [210]. 

Note that when the defect concentration was intrinsically controlled, the activation energy for its formation appeared in the final expression for D [i.e., Eq. (7.20)], whereas when the concentration of the defects was extrinsically controlled, the final expression included only the energy of migration. How this fact is used to experimentally determine both A//, and A//5 is discussed in the following worked example. 

Optionally, migratory cells lacking the respective chemokine receptor can be added. These cells—in our case Ccr7-deficient dendritic cells—are unable to sense any differences in chemokine concentration but are stiU able to migrate within the chamber in a random pattern and are therefore perfectly suited as an intrinsic control. 

After harvesting and optional staining, cells are resuspended in chamber medium. Cells are counted and mixed to a final concentration of 4-8 X 10 /ml reporter cells (including intrinsic controls) and 8—16 X 10 /ml consumer cells. In our hands, this concentration is perfectly suited to acquire a moderate cell density that balances the estabhshment of a gradient and also allows single-cell tracking. Naturally, these numbers may not be ideal in assays using different cell types. 

Systems such as sac-type blood pumps have been described as having intrinsic automatic control. That is, these devices can run in a fill limited mode, and as more blood is returned to the pump, it increases its stroke volume. Intrinsic control is desirable, but unfortunately, this generally provides for only a limited control range, and in rotary blood pumps this sensitivity may be even less. 

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