We describe a program to demonstrate the scientific basis of magnetized target fusion (MTF). MTF is a potentially low-cost path to fusion which is intermediate in plasma regime between magnetic (MFE) ...and inertial fusion energy (IFE). MTF involves the compression of a magnetized target plasma and pressure times volume (PdV) heating to fusion relevant conditions inside a converging flux conserving boundary. We have chosen to demonstrate MTF by using a field-reversed configuration (FRC) as our magnetized target plasma and an imploding metal liner for compression. These choices take advantage of significant past scientific and technical accomplishments in MFE and defense programs research and should yield substantial plasma performance (n/spl tau/>10/sup 13/ s-cm/sup -3/ T>5 keV) using an available pulsed-power implosion facility at modest cost. We have recently shown the density, temperature, and lifetime of this FRC to be within a factor of 2-3 of that required for use as a suitable target plasma for MTF compression for a fusion demonstration.
Plasma Wave Observations at Comet Giacobini-Zinner Scarf, Frederick L.; Coroniti, Ferdinand V.; Kennel, Charles F. ...
Science (American Association for the Advancement of Science),
04/1986, Letnik:
232, Številka:
4748
Journal Article
Recenzirano
The plasma wave instrument on the International Cometary Explorer (ICE) detected bursts of strong ion acoustic waves almost continuously when the spacecraft was within 2 million kilometers of the ...nucleus of comet Giacobini-Zinner. Electromagnetic whistlers and low-level electron plasma oscillations were also observed in this vast region that appears to be associated with heavy ion pickup. As ICE came closer to the anticipated location of the bow shock, the electromagnetic and electrostatic wave levels increased significantly, but even in the midst of this turbulence the wave instrument detected structures with familiar bow shock characteristics that were well correlated with observations of localized electron heating phenomena. Just beyond the visible coma, broadband waves with amplitudes as high as any ever detected by the ICE plasma wave instrument were recorded. These waves may account for the significant electron heating observed in this region by the ICE plasma probe, and these observations of strong wave-particle interactions may provide answers to longstanding questions concerning ionization processes in the vicinity of the coma. Near closest approach, the plasma wave instrument detected broadband electrostatic noise and a changing pattern of weak electron plasma oscillations that yielded a density profile for the outer layers of the cold plasma tail. Near the tail axis the plasma wave instrument also detected a nonuniform flux of dust impacts, and a preliminary profile of the Giacobini-Zinner dust distribution for micrometer-sized particles is presented.
A prospective study of 1,144 infants and their families was performed. Smoking and family histories were evaluated with respect to the incidence of lower respiratory disease during the first year of ...life. It was found that (1) tracheitis and bronchitis occurred significantly more frequently in infants exposed to cigarette smoke in the home, (2) maternal smoking imposed greater risks upon the infant than paternal smoking, (3) occurrence of neither tracheitis nor bronchitis showed a consistent relationship to the number of cigarettes smoked, (4) a family history that was positive for respiratory illness (chronic cough or bronchitis) significantly influenced the incidence of bronchitis, (5) too few cases of laryngitis and pneumonia were seen to warrant any opinions regarding the adverse influence of either smoking or a family history that was positive for respiratory illness, and (6) occurrence of bronchiolitis was not affected by the presence of a smoker nor influenced by a family history that was positive for respiratory illness. It is concluded that passive smoking is dangerous to the health of infants and that infants born to families with a history that is positive for respiratory illness (chronic cough or bronchitis) are at risk of developing bronchitis.
We analyzed the long-term functional results in 102 eyes of 59 patients with childhood glaucoma with specific reference to the pattern of optic nerve damage. Optic disk photography and quantitative ...perimetry were used to judge the degree of damage that had been sustained. There was a predilection for initial visual field damage in the arcuate area, followed by further arcuate and nasal field loss, similar to the pattern of visual field loss seen in adult glaucoma. In children, as in adults, neural tissue appeared to be lost preferentially at the vertical disk poles. The selective pattern of glaucomatous optic nerve damage seemed not to depend upon the age of the optic nerve structures. In contrast to adult eyes, the scleral canal in children apparently enlarges with high IOP. Thus, disk cup size increase in children could occur from neural tissue loss, from scleral canal enlargement, or from a combination of the two processes.
A distributed multimedia conferencing system Ng, J.M.; Chan, E.; Ip, H.H.S. ...
Proceedings / TENCON '93, 1993 IEEE Region 10 Conference on "Computer, Communication, Control, and Power Engineering", October 19-21, 1993, Beijing, Beijing International Convention Center, Beijing Continental Grand Hotel,
1993, Letnik:
1
Conference Proceeding, Journal Article
We present the design of a desktop multimedia conferencing system, called Nebula, built with a distributed conference control infrastructure with fault tolerance capability. The system provides for ...considerable flexibility in conferencing facilities: it supports three different modes of floor control passing and switching between these modes during a conference. Conferees can join a conference in various ways, with selection of chairperson according to seniority defined in the agenda file. To handle the concurrency problem, only the floor holder can modify shared data in the public windows. Each conferee holds a copy of shared data and only update operations are sent so as to improve response time and minimize network traffic. A simple and well defined application user interface (API) is provided and a number of multimedia applications has been developed using the API.< >
