Field bursts

A time diagram of the electric field bursts (5.1.1) is shown in Fig. 5.3. A planar rotor perturbed by a sequence of delta kicks according to (5.1.1) is known as the kicked rotor. In order to familiarize ourselves with the physics of kicked systems, we focus in this section on the classical mechanics of the kicked rotor. If we denote by L the angular momentum of the rotor, the Hamiltonian function of the kicked rotor is given by... 

Fig. 5.3. Time diagram of the electric field bursts of the kicked rotor model.

Near-field blast effects were found to be highly directional for the spheroid burst and the cylindrical detonation. 

The method presented above is based on the similarity of the blast waves of pressure vessel bursts and high explosives. This similarity holds only at some distance from the explosion. In the near field, the peak overpressure and impulse from a pressure... 

Di-D-fructose dianhydrides were first reviewed in 1946 as part of a chapter1 in this Series. That work described the outcome of a burst of activity in this field,... 

Fig. 24. Comparison of effect of viscosity ratio on reduced burst time for rotational and irro-tational shear fields [76]...

A seizure is accompanied by a burst of spikes in the EEG. Between these so-called iclal phases are solitary EEG interictal spikes. Each of them represents the field potential associated with a burst of action potentials in a group of neurons within the epileptic focus (Fig. 16.2). 

Barth s-Biesel, D., and Acrivos, A., Deformation and burst of a liquid droplet freely suspended in a linear shear field. J. Fluid Mech. 61,1-21 (1973). 

An explosion occurs when energy previously confined is suddenly released to affect the surroundings. Small explosions, like the bursting of a toy balloon, are familiar and innocuous, but large-scale explosions, like an atomic bomb, are rare and usually disastrous. Between these two extremes lie the commercial and conventional military fields where explosions are produced on a limited scale to cause specific effects. It is with explosions of this intermediate scale that this book is concerned. 

The effect of ultrasound on liquid-liquid interfaces between immiscible fluids is emulsification. This is one of the major industrial uses of ultrasound (74-76) and a variety of apparatus have been devised which will generate micrometer-sized emulsions (9). The mechanism of ultrasonic emulsification lies in the shearing stresses and deformations created by the sound field of larger droplets. When these stresses become greater than the interfacial surface tension, the droplet will burst (77,78). The chemical effects of emulsification lie principally in the greatly increased surface area of contact between the two immiscible liquids. Results not unlike phase transfer catalysis may be expected. 

Another instructive example of the relevance of ambient stimuli to the nature of the effect of serotonergic manipulations on locomotor activity is provided by Brody s (27) study of PCPA. He monitored the locomotion of vehicle- and PCPA-treated rats in an open field to which the animals had been previously familiarized. Animals were tested either with or without additional stimulation in the form of flashing lights and 90 dB(A) noise bursts. Without stimulation, PCPA-treated rats were less active than controls with stimulation, PCPA-treated rats were more active. The results of these and other such studies indicate that the central serotonergic systems may not directly modulate the level of locomotor activity per se, but they may profoundly influence locomotor activity by virtue of their effects on the sensory responsivity of the animal to a wide variety of environmental stimuli. 

Abstract Gamma-ray bursts are the most luminous and probably the most relativistic events in the universe. The last few years have seen a tremendous increase in our knowledge of these events, but the source of the bursts still remains elusive. I will summarize recent progress in this field with special emphasis on our understanding of the possible progenitor systems. 

There are various ways how this huge field strength could be used to produce a GRB. The fields in the vortex rolls (see Fig. 8 in Rosswog and Davies 2002) will wind up the magnetic field fastest. Once the field reaches a strength close to the local equipartition value it will become buoyant, float up, break through the surface and possibly reconnect in an ultra-relativistic blast (Kluzniak and Ruderman 1998). The time structure imprinted on the sequence of such blasts would then reflect the activity of the fluid instabilities inside the central object. The expected lightcurve of the GRB would therefore be an erratic sequence of sub-bursts with variations on millisecond time scales. 

---