Stress electric shock

An example for stimulus generalization are responses of rats to stress-inducing odors. Laboratoiy rats of the Wistar strain respond to predator odors, specifically mercapto compounds in fox droppings, with stress reactions, for example avoidance behavior such as freezing and increased plasma corticosterone concentrations (Vemet-Mauiy et ah, 1984). The rats were trained to avoid water scented with a mercapto odorant that contained both a keto- and a sulfhydryl group (4-mercapto-4-methyl-2-pentanone). As the animals licked a waterspout, a mild electric shock was applied to their tongue. When different compounds were tested thereafter, the rats avoided compounds with similar... 

High/low/changing temperature and pressure Stress concentrations, stress reversals, vibration, noise Structural damage or failure, falling objects, collapse Electrical shock and thermal effects, inadvertent activation, power source failure... 

Another method of neurotoxicant entry into the CNS is by exploitation of a compromised blood-brain barrier. Aluminum itself compromises the blood-brain barrier and reactive species, both directly and indirectly, can open the barrier. Blood-borne inflammation, possibly through the release of reactive oxygen species, is widely known to create a leaky blood-brain barrier. This allows inflammatory cells, endotoxins, and neurotoxicants to enter the CNS. Inflammation within the brain itself also affects blood-brain barrier permeability, an aspect that potentially links psychological stress to increased susceptibility to neurotoxicants. It has been shown that inflammatory responses are induced in animals under stressful conditions, such as electrical shock, restraint, or adverse social interactions. 

It has been demonstrated that the hippocampal cholinergic system is actively involved in stress response. Acute and chronic stress-induced changes in synaptic ACh release and choline uptake (parameter of cholinergic system) have been studied in rat hippocampus. Acute as well as chronic intermittent immobilization stress increased ACh release whereas, choline uptake increased after acute stress and decreased after chronic stress. Repeated cold stress has been shown to decrease the total ACh content in basal ganglia and hypothalamus, whereas its amount increased in the duodenum of rat. Similarly, cold stress resulted in a decrease of ACh levels in the hypothalamus and hippocampus of rat. It has been assumed that the stores of ACh in the hippocampus of a rat that are exposed to stress may become depleted. However, Costa et al. ° and Mizukawa et al. failed to find any change in rat ACh after stress. After electric shock stress, the ACh concentration was found to be depleted in brain regions of rat and mice. Following 2 h of mild restrain stress, choline uptake was increased in hippocampus, septum, and frontal cortex of rat. " The administration of chronic electric shock to rats has increased the ACh content in the medulla. ... 

But the worm research did have some interesting spin-offs. Mice that were fed the brains and livers of other mice subjected to stress — researchers had rolled them around in glass jars — learned to associate a light stimulus with electric shock faster than other test animals. It seems that stress hormones transferred by diet enhanced learning. 

As the next step, an analysis of the consequences of jets should be performed. The following effects of jets on targets should be taken into account mechanical load (pressure, impact), thermal load (temperature, including thermal stresses and shocks where appropriate) and properties of fluids (such as possible short circuits in electric equipment due to the conductivity of liquid water). Possible chemical effects should also be taken into account, especially if the fluid ejected is other than water. It may be... 

It is estimated that office workers sustain 76,000 fractures, dislocations, sprains, strains, and contusions each year. In office areas, trips and falls are the number one cause of injury. Office workers are also injured as a result of foreign substances in the eye, spilled hot liquids, burns from fire, and electric shock. The office may also contain hazards such as poor lighting, noise, poorly designed furniture and equipment, and machines that emit noxious gases and fumes. Even the nature of office work itself has produced a whole host of stress-related symptoms and musculoskeletal strains. 

In this chapter, the applicable environmental factors include temperature, vapor phase and condensed moisture, corrosive inorganic gases, organic vapors, particles, electric fields, and air velocity. While vibration, mechanical stress, thermal shock, and solar radiation can occasionally contribute to materials degradation in indoor environments, these subjects are covered in other chapters and MIL-STD-810E. 

The communication box was used to provide psychological stress. The box consisted of small compartments (10 x 10 cm) equipped with either an electric foot-shock floor or a non-shock floor, and the electric shock and the non-shock floor were placed reciprocally. A mouse (sender) placed on an electric shock floor made emotional responses when charged with electricity to the floor for 10 sec at intervals of 50 sec and a mouse (responder) placed in a non-shock floor were exposed only to psychological stress. The electric current for the shock was increased stepwise from 1.6 mA to 2.0 mA at the rate of 0.2 mA per 1 h over 3 h. Sender mice were changed daily to naive mice in order to avoid reduced emotional responses to the electric shock due to adaptation to repeated exposures. Responder mice were daily administered with either AGE (10 ml/kg) or water (control) one hr prior to the 3 h emotional stress for 4 days. On day 1, responder mice were immunized with sheep red blood cells (SRBC, 1 X10 ) after the 3 h stress. After the last day of stress exposure, the spleen weight and number of spleen cells were measured and the number of anti-SRBC plaque-forming-cells (PEC) were assayed. 

Ceramics are subject to failure by thermal shock due to the disruptive stresses that result from the differential dilation between the surface and core of a body. With the relatively slow cooling rates usually encountered in most electrical and electronic applications and with the exception of materials with very low thermal expansion coefficients, the thermal conductivity usually determines the resistance of a ceramic to failure by thermal shock. Listed in Table 2.2 are the thermal stresses or shock resistances of several ceramics as derived from the relation R" = C oIccE, where C is the thermal conductivity, o is the tensile strength, a is the coefficient of thermal expansion, and E is Young s modulus. 

Certainly the most prominent feature of the breakdown process is its dependence on the polarity of the electric field relative to the shock-velocity vector. This effect is manifest in current pulse anomalies from minus-x orientation samples or positively oriented samples subjected to short-pulse loading (see Fig. 4.8). The individual effects of stress and electric field may be delineated with short-pulse loadings in which fields can be varied by utilizing stress pulses of various durations [72G03]. 

Fig. 4.9. The data of Fig. 4.8 are represented in the electric-field, stress plane to show that the anomalous response occurs above a critical stress and critical electric field. The response is found to be due to dielectric loss or shock-induced conduction (after Davison and Graham [79D01]).

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