Types of Response

It is very important, from one hand, to accept a hypothesis about the material fracture properties before physical model building because general view of TF is going to change depending on mechanical model (brittle, elasto-plastic, visco-elasto-plastic, ete.) of the material. From the other hand, it is necessary to keep in mind that the material response to loads or actions is different depending on the accepted mechanical model because rheological properties of the material determine type of response in time. The most remarkable difference can be observed between brittle materials and materials with explicit plastic properties. 

Carbon tetrachloride is toxic by inhalation of its vapor and oral intake of the Hquid. Inhalation of the vapor constitutes the principal ha2ard. Exposure to excessive levels of vapor is characterized by two types of response an anesthetic effect similar to that caused by compounds such as diethyl ether and chloroform and organic injury to the tissues of certain organs, in particular the Hver and kidneys. This type of injury may not become evident until 1—10 days after exposure. The nature of the effect is deterrnined largely by the vapor concentration but the extent or severity of the effect is deterrnined principaHy by the duration of exposure (38). 

This type of response is referred to as non-linear viscoelastic but as it is not amenable to simple analysis it is often reduced to the form... 

This equation is the basis of linear viscoelasticity and simply indicates that, in a tensile test for example, for a fixed value of elapsed time, the stress will be directly proportional to the strain. The different types of response described are shown schematically in Fig. 2.1. 

Under the hazardous waste standard, on-site emergeney responders, on-site eollateral-duty emergeney responders, and off-site emergeney responders are trained to one or more of five levels of eompeteney, depending on the type of response they perform as speeified in 29 CFR 1910.120 (q). 

Practical problems with hemi-equilibria can be avoided by allowing sufficient time for equilibrium to occur. However, there are some situations where this may not be possible. One is where the functional system desensitizes during the span of time required for equilibrium to be attained. Another is where the actual type of response being measured is transitory and where the only measurement of calcium transients where a spike of effect is the only response observed in the experimental system. 

This may be understood more fully by reference to Fig. 11.2. Curve A shows the type of response which would be obtained if the lethal process followed precisely the pattern of a first-order reaction. Some experimental curves do, in fact, follow this pattern quite closely, hence the genesis of the original theory. 

Antigens, however, can induce a second type of response which is known as the cell-mediated immune response. The antigenic agent stimulates the appearance of sensitized lymphocytes in the body which confer protection against organisms that have the ability to live and replicate inside the cells of the host. Certain of these lymphocytes are also involved in the rejection of tissue grafts. 

In 1980, the U.S. Congress enacted the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the first comprehensive federal law addressing the protection of the environment from the threat of hazardous substances. The primary goal of CERCLA is to establish an organized cost-effective mechanism for response to abandoned or uncontrolled hazardous waste sites that pose a serious threat to human health and the environment.8 9 To accomplish this goal, two types of response capabilities are mandated by CERCLA13 ... 

Figure 1.2 Negative feedback. These types of responses are employed throughout the body in order to maintain homeostasis. In this example, any change in blood pressure, which is monitored within the circulatory system and processed within the CNS, will cause reflex changes in heart rate. The change in heart rate will be in the opposite direction of the change in blood pressure if blood pressure increases, then heart rate decreases if blood pressure decreases, then heart rate increases. In this way, blood pressure is adjusted back to its normal value.

Acceptable limits may differ considerably for the measured property values, however. For a majority of cases, responses can be classified as having either a maximum acceptable value, a minimum acceptable value, or a most desirable value within an acceptable range. For each response, these cases may be incorporated into a desirability factor having the range 0 < d < 1 with d 0 denoting an unacceptable response value and d 1 representing totally acceptable behavior. Intermediate values are determined by equations (22) based on the acceptable limits, the desired response value, and the type of response behavior desired by the formulator. 

Inducible or repressible refers to the type of response the system makes to the presence of a metabolite. Inducible genes are turned on when they sense the presence of a metabolite. Usually, this means that the metabolite is a precursor of something the cell needs. If the precusor is present, inducible genes are turned on to metabolize it. Repressible genes are turned off by the presence of a metabolite. These genes are usually involved in the synthesis of the metabolite. If the cell has enough of the metabolite, the pathway is turned off (repressed). If the metabolite is not present, the pathway is turned on. 

The dashed curve in Figure 9B gives the approximate, smoothed result that would have been obtained if the catalyst response were instantaneous. The area between the dashed curve and the actual response represents additional CO conversion due to the noninstantaneous dynamic response of the catalyst. This type of response is desirable because it will lead to low CO emissions when the air-fuel ratio cycles about the stoichiometric point. 

Figure 2-8 The various types of response vs. log dose curves. ED, effective dose TD, toxic dose LD, lethal dose. For gases, LC (lethal concentration) is used.

The relationship between the various types of response-log dose curves is shown in Figure 2-8. 

This P -I type of response curve can also be easily shown to apply to a simple rigid-plastic mechanical system, in the manner shown in Figure 16 (see Refs. 15 and 22). Here, the spring in the system is replaced with a pure Coulomb friction element, with resisting force f, which is independent of displacement once the mass starts to move. All other symbols are defined above. 

A second form of delayed-type hypersensitivity response is similar to that of contact dermatitis in that macrophages are the primary effector cells responsible for stimulating CD4+ T cells however, this response is not necessarily localized to the epidermis. A classical example of this type of response is demonstrated by the tuberculin diagnostic tests. To determine if an individual has been exposed to tuberculosis, a small amount of fluid from tubercle bacilli cultures is injected subcutaneously. The development of induration after 48 h at the site of injection is diagnostic of prior exposure. 

Shock, similar to that of anaphylaxis, may occur as a third form of a delayed systemic hypersensitivity response. However, unlike anaphylaxis, IgE antibodies are not involved. This type of response may occur 5-8 h after systemic exposure and can result in fatality within 24 h following intravenous or intraperitoneal injection. 

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