The measurement of an acoustic emission, or scatter, from a bubble is not difficult. However, an accurate interpretation of that signal in terms of the bubble dynamics may require careful consideration. The study presented here is at first sight relatively simple: comparison of the predicted and measured quality factors of injected bubbles. While the measurement is normally done by monitoring the decay of passive emissions from a bubble, this technique becomes difficult with smaller bubbles. Therefore an active technique is introduced, which removes all the frequency-dependent effects on the measurement (such as transducer response) bar one. That, critically, is the effect of the change in the bubble resonance (frequency and damping) which results from the loading on the bubble due to the reverberant field. The vast majority of theoretical treatments of bubble acoustics assume free field conditions, yet the environmental conditions rarely if ever match these. Therefore measurements of bubble damping are compared both with the established free field theory, and with a new theory relevant to the prevailing reverberant conditions (whether caused by tank surfaces, monochromatic neighboring bubbles, or both).

Recent studies of lynching have focused on structural theories that have been tested with demographic, economic and electoral data without much explanatory success. This article suggests that lynching was largely a reflection of a facilitating subculture of violence within which these atrocities were situationally determined by cultural factors not reported in census and economic tabulations, or election returns. Lynching declined in the twentieth century, in part, as a result of segregation and disfranchisement policies, but mainly because state executioners replaced lynch mobs in carrying out the will of the white majority.On Sunday afternoon, 23 April 1899, Sam Hose was lynched after church services in Palmetto, Georgia. Hose had admitted killing his employer in self-defence when the latter tried to shoot him during a dispute over wages. To that undisputed fact was added the totally fictitious rumour that Hose had also sexually assaulted the slain man's wife. The Atlanta Constitution offered a five-hundred dollar reward for Hose's capture, announcing that he would be burned alive. Bulletins were subsequently tacked up everywhere people gathered, announcing the place and date of the scheduled burning. Public interest was so aroused that special excursion trains were scheduled to carry curious spectators from Atlanta. Ladies clothed in their Sunday finery watched from carriages, gazing excitedly over the heads of men carrying small children on their shoulders as the ritual began.Hose was led to a stake placed in the middle of a dirt road. There he was bound with chains. Yelps and cheers rose from the throng of some two thousand people as Hose's ears were sliced off and thrown to anxious onlookers. As he writhed in agony, fingers and toes were amputated before the screaming man's tongue was removed with a pair of pliers. Only then was the coal oil poured ceremoniously over his prostrate body. There was a loud cheer as he was set aflame. When the flames receded, the charred corpse was eviscerated, an enterprising Georgian removing internal organs to sell as souvenirs. Bones went for a quarter; slices of his heart and liver were cheaper at ten cents each. And

Gamma Knife SRS is a safe and feasible strategy for treatment of patients with a single radioresistant brain metastasis. Radiosurgery alone is a reasonable treatment option, but may carry a greater likelihood of distant brain recurrence.

Models for the acoustic cross-sections of gas bubbles undergoing steady-state pulsation in liquid have existed for some time. This article presents a theoretical scheme for estimating the cross-sections of single bubbles, and bubble clouds, from the start of insonation onward. In this period the presence of transients can significantly alter the cross-section from the steady-state value. The model combines numerical solutions of the Herring-Keller model with appropriate damping values to calculate the extinction cross-section of a bubble as a function of time in response to a continuous harmonic sound field (it is also shown how the model can be adapted to estimate the time-dependent scatter cross-section). The model is then extended to determine the extinction cross-section area of multiple bubbles of varying population distributions assuming no bubble-bubble interactions. The results have shown that the time taken to reach steady state is dependent on the closeness of the bubble to resonance, and on the driving pressure amplitude. In the response of the population as a whole, the time to reach steady state tends to decrease with increasing values of the driving pressure amplitude; and with the increasing values of the ratio of the numbers of bubbles having radii much larger than resonance to the number of resonant bubbles. The implications of these findings for the use of acoustic pulses are explored.

Several years ago James Q. Wilson studied the members of the three amateur Democratic clubs in New York, Chicago, and Los Angeles. He intended his study, by his own admission, to be interesting rather than theoretical, but we have found its theoretical portions to be intriguing. The amateur politicians studies by Wilson primarily concentrated their energies in local politics, although their ambitions extended far beyond local campaigns and issues. Indeed, they expressed a clear desire to alter fundamentally the character of the American party system and, accordingly, all governing institutions.Wilson's task of identifying and characterizing the political motives and tactics of amateur Democrats was facilitated by the existence of political clubs. He had only to identify the clubs he wished to study and survey their members. Future researchers were left the responsibility of identifying similar political motives and tactics in less well-defined groups. We attempted to do this for a sample of delegates to the Democratic National Convention in 1968, and, following Wilson's criteria, we were successful in identifying a substantial proportion of amateur Democrats.The amateur Democrat described by Wilson was not set apart from the more conventional party activitsts by his liberalism, his age, education or class. He was not a dilettante or an inept practitioner of politics, nor did he regard politics as an avocation or hobby. Rather the amateur found politics intrinsically interesting because it expressed a conception of the public interest. The political world was perceived in terms of policies and principles which were consistent with the amateur's theory of deomocracy.