Feedback process

Feedback Processes Involving Marine Chemistry and Climate... 

DMS has been observed in the marine atmosphere since the early 1970s, but it was not until the mid-1980s that there was interest in this gas as being a natural source for sulfate CCN. Sulfate aerosols are, in number terms, the dominant source of CCN. The major role clouds play in the climate system leads to possible climatic implications if changes to DMS production occurred. Furthermore, the dependence of this production on environment conditions means that scope for a feedback process arises this feedback is called the Charlson hypothesis. ... 

Many climatically sensitive feedback processes could be described in addition to those outlined above. We have restricted our attention to processes that have potentially large effects. A large effect is defined as one that could change the current rate of atmospheric CO2 increase by at least 50% ( 1 Pg C-yr"" ). 

At its most fundamental level, the circadian cycle rests on the influence of so-called clock genes . These genes have been studied most extensively in insects but they have also been found in humans. Their protein products enter the cell nucleus and regulate their own transcription. This feedback process is linked to exposure to light and so it is not surprising that visual inputs are important for maintenance of circadian rhythms. However, it is not the reception of specific visual information, transmitted in the optic nerve to the lateral geniculate nucleus (LGN) and visual cortex (i.e. visual discrimination), that is responsible for the rhythm but the more simple, almost subconscious, reception of light. 

Kauffman also considers that autocatalytic reactions are a necessary precondition for biogenesis processes, as they can wind themselves up via self-amplifying feedback processes until a critical boundary has been reached. The next step would then be the transition from autocatalysis to self-organisation, similar to the transition from unstructured water to convection cells (the Benard instability) (Davies, 2000). 

The accretion history of a parent galaxy is constructed using a semi-analytical code. The full phase-space evolution during each accretion event is then followed separately with numerical simulations [2]. Star-formation and chemical evolution models are implemented within each satellite. The star formation prescription matches the number and luminosity of present-day galaxies in the Local Group, whereas the chemical evolution model takes into account the metal enrichment of successive stellar populations as well as feedback processes. Below we present results of a sample of four such simulated galaxy halos, denoted as Halos HI, H2, H3 and H4. 

Odorant recognition initiates a second-messenger cascade leading to the depolarization of the neuron and the generation of action potentials 821 Negative-feedback processes mediate adaptation of the olfactory transduction apparatus to prolonged or repetitive stimulation 823 Alternative second-messenger pathways maybe at work in olfactory transduction 823... 

In this case, which may be regarded as the opposite extreme to the Simple model, it is supposed that, through feedback processes, accretion occurs at just such a rate as to compensate the loss of gas in star formation, i.e. 

The faster the climate warms up, the more likely it is that feedback processes will change the greenhouse gas buildup. There are many that believe that C02 and other trace greenhouse gases could double sometime within the next century. 

Biological feedback processes can be expected to affect the amounts of carbon dioxide that might be injected into the air over the next century. 

Kronzucker HJ, Schjoerring JK, Emer Y, Kirk GJD, Siddiqi MY, Glass ADM. 1998b. Dynamic interactions between root NH4+ influx and long-distance N translocation in rice insights into feedback processes. Plant and Cell Physiology 39 1287-1293. 

There is thus a multiplicity of negative feedback processes that could, in principle, give rise to oscillations in Notch signaling, and on which the... 

Fig. 3.10 Thermal structure of a combustion wave and heat feedback processes therein.

Fig.s.n Schematic representation of heat feedback processes in a combustion wave. 

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