Feedback amplification

Moreover, a recent study also revealed that ROS generation led to the activation of caspase-2 during p-carotene-induced apoptosis in the human leukemic T cell line Molt 4. The apoptosis progressed by simultaneous activation of caspase-8 and caspase-9, and a cross talk between these initiator caspases was mediated by the pro-apoptotic protein Bid. Inhibition of caspases 2, 8, 9, and 3 independently suppressed the caspase cascade. The cleavage of the anti-apoptotic protein BclXL was found to be another important event during P-carotene-induced apoptosis, suggesting the presence of an extensive feedback amplification loop in P-carotene-induced apoptosis (Prasad et al., 2006). 

Prasad, V., Chandele, A., Jagtap, J.C., Sudheer, K.P., and Shastry P. 2006. ROS-triggered caspase 2 activation and feedback amplification loop in beta-carotene-induced apoptosis. Free Radio Biol Med 41 431 442. 

Once the formation of the clot (thrombus) begins, clot formation is accelerated in an almost explosive manner by a number of processes collectively termed feedback amplification. 

The test-tube model of coagulation consists of the extrinsic pathway, the intrinsic pathway and a common pathway as shown in Figure 19.3. Damage to a blood vessel exposes TF to the blood, initiating the TF pathway or extrinsic pathway. TF binds zymogen and factor VII to produce activated factor Vila. Factor Vila activates factor X to factor Xa in the common pathway as well as factor IX to factor IXa in the contact activation (intrinsic) path-way,2o.2i jjjjg jg jgygj Qf positive feedback amplification. Activated... 

The open-loop characteristics can be obtained by means of an external digital-to-analog converter (DAC) and analog-to-digital converter (ADC) with a harmonic response scan. The frequency response of the open loop outside the operational range is essential to ensure the system stability. After the initial open-loop response is obtained, the filter correction is made to adjust the feedback amplification, to make a flat response in the passband and predetermined behavior at low-and high-cutoff frequencies. The process is iterative in the same way as it was for the non-feedback devices. 

Figure 17.4 The kinin cascade. Solid arrows represent biochemical conversions whereas dotted lines represent catalytic activity. Note that kallikrein provides amplification in the process (positive feedback).

The system is constructed hierarchically which allows an amplification of the signals registered in the hypothalamus. The hypothalamus-pituitary path can uptake nerve impulses and translate them into specific hormone production. A further characteristic of the system are regulatory mechanisms with whose help the formation and secretion of hormones can be controlled. The circulating hormone exerts a feedback inhibition at various levels thus ensuring that an overproduction of hormones is avoided. 

Producing energy amplification by dual interaction of multiple simultaneous processes in a coil, with iterative feedforward and feedback between the simultaneous interactions... 

However, if the electric resistivity is taken into account, there appears in general a new, very fundamental circumstance the normal component of the Laplacian of an arbitrary vector also depends on the tangential components of the vector. The magnetic viscosity creates feedback, due to which the tangential components are able to modify (in particular, to amplify) the normal component. Therefore, in principle, exponential, coordinated amplification of all fields also becomes possible, i.e., a dynamo But this is a peculiar kind of dynamo that depends on the magnetic viscosity. 

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