Transmission of megawatt relativistic electron beams through millimeter apertures.

High-power, relativistic electron beams from energy-recovering linacs have great potential to realize new experimental paradigms for pioneering innovation in fundamental and applied research. A major design consideration for this new generation of experimental capabilities is the understanding of the halo associated with these bright, intense beams. In this Letter, we report on measurements performed using the 100 MeV, 430 kW cw electron beam from the energy-recovering linac at the Jefferson Laboratory's Free Electron Laser facility as it traversed a set of small apertures in a 127 mm long aluminum block. Thermal measurements of the block together with neutron measurements near the beam-target interaction point yielded a consistent understanding of the beam losses. These were determined to be 3 ppm through a 2 mm diameter aperture and were maintained during a 7 h continuous run.

Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment.

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.

Plasmid profile analysis of salmonellae in a large-animal hospital.

The plasmid profiles of salmonellae isolated from the patients and environment of the Purdue Large Animal Hospital were used as markers to identify strains and to assess the impact of improvements in hospital operation on nosocomial salmonellosis. Plasmid profile analysis proved to be more sensitive than either serotyping or antimicrobial susceptibility testing in identifying Salmonella isolates. During June and July 1983, 29 of 34 salmonellae isolated were one of three strains with distinct plasmid profiles: one S. typhimurium var. Copenhagen, and two S. muenchen. Each of these strains was isolated from at least one patient and two environmental sites, suggesting the possibility that infections were hospital-acquired. Patient and environmental sampling was repeated in June and July 1984, after improvements had been made in hospital traffic flow and sanitation. In contrast to 1983, only seven isolates, representing six strains not seen previously, were obtained in 1984. None of these strains was isolated from both patient and environmental sources. The results indicate that the high incidence of clinical salmonellosis in 1983 was largely due to nosocomial infections. The decrease in the incidence of salmonellosis and the absence of the 1983 strains from samples taken in 1984 were presumed to be due to improvements made in hospital operation. This study demonstrates the value of plasmid analysis in monitoring nosocomial salmonellosis in a veterinary hospital.

Plasmid profile analysis of bovine isolates of Pasteurella haemolytica.

Pasteurella haemolytica isolates, obtained from cattle with respiratory tract disease, were characterized as to serotype, antimicrobial susceptibility, and plasmid content. Strains isolated from 2 groups of cattle were compared. Remarkable similarity was seen in the plasmid profiles of isolates of the same serotype. In contrast, isolates of 2 different serotypes had totally different plasmid profiles.

Poor man's LMA: achieving adequate ventilation with a poor mask seal.

PURPOSE: This report describes a technique of ventilation prior to laryngoscopy and intubation that proved to be simple, inexpensive and effective for a patient whose airway evaluation suggested difficult mask ventilation. The technique is called Poor Man's LMA. CLINICAL FEATURES: A 60-yr-old male, measuring 170 cm, weighing 117 kg, edentulous and with a full beard, was to undergo uvulopalatopharyngoplasty. After induction of general anesthesia with a hypnotic, analgesic and non-depolarizing muscle relaxant, it was soon determined that mask bag ventilation was difficult due to an inadequate seal between the mask and the patient's full beard. To improve ventilation, an endotracheal tube was placed into the oropharynx, the lips and nose compressed by a colleague in order to prevent gas egress, and effective manual ventilation established by connecting the circle system to the endotracheal tube. Subsequent direct laryngoscopy and intubation were accomplished without incident. CONCLUSION: The patient's clinical features made conventional mask bag ventilation difficult and inadequate. The Poor Man's LMA technique improved oxygenation and ventilation in preparation for intubation. Further investigations on the usefulness of this technique are warranted.

Vessel dilator cricothyrotomy for transtracheal jet ventilation.

Needle cricothyrotomy is a safe, relatively easy procedure and has been described to enable pulmonary ventilation for patients in both elective and emergency situations. Conventional IV cannulae are short, thin-walled, and easily kinked and, therefore, do not provide a secure system to jet oxygen into the trachea. The vessel dilators of most 7-9 French introducer kits are firm, pliable, resist kinking, and can be passed easily into the tracheal lumen. We describe our experience with the use of vessel dilator cricothyrotomy to oxygenate and ventilate the lungs of patients in emergency and elective situations.

Selection of nonmucoid derivatives of mucoid Pseudomonas aeruginosa is strongly influenced by the level of iron in the culture medium.

We investigated the effects of cations on the stability in culture of mucoid strains pf Pseudomonas aeruginosa isolated from patients with cystic fibrosis by studying their effects on the selection of nonmucoid derivatives which arise by spontaneous mutation in cultures of mucoid organisms. Calcium ion concentrations in the range 0.55 to 1.85 mM had no effect on the growth or stability of the mucoid cultures. Higher levels (5.0 mM) inhibited the growth of both mucoid and nonmucoid cells. Likewise, magnesium ion in concentrations of 0.3 to 3.0 mM had no effect. The concentration of iron (either Fe2+ or Fe3+) had a profound effect on the selection of nonmucoid mutants in unshaken cultures of mucoid organisms. In medium containing 0.01 mM iron, nonmucoid mutants rapidly accumulated to a greater than 100-fold-higher frequency than the mucoid forms. Rates of accumulation of nonmucoid derivatives were lower in media containing lower concentrations of iron. The possible role of iron in the selection of nonmucoid cells from a population of mucoid P. aeruginosa is discussed.

Motility as a selective force in the reversion of cystic fibrosis-associated mucoid Pseudomonas aeruginosa to the nonmucoid phenotype in culture.

Motility acted as a strong positive selection for nonmucoid Pseudomonas aeruginosa in unshaken cultures. Consistent with this finding, electron microscopic examination of mucoid and nonmucoid revertant strains indicated that the mucoid cells were nonflagellated whereas the nonmucoid revertants were flagellated.

Effects of halothane on the pharmacokinetics of lidocaine in digitalis-toxic dogs.

Following the production of digitalis toxicity in dogs as manifested by ventricular tachycardia, the pharmacokinetics of lidocaine treatment of the arrhythmia were determined during pentobarbitone anaesthesia and pentobarbitone-halothane anaesthesia. The elimination rate constants, beta and Ke, and the biological half life T1/2beta were statistically significantly increased during halothane anaesthesia. The volume of distribution was unchanged. The results indicate that the therapeutic loading dose of lidocaine need not be altered during halothane anaesthesia but if a constant infusion is used, the rate of infusion would have to be decreased four fold to avoid toxic plasma levels of lidocaine.

Early diagnosis of Rocky Mountain spotted fever. Use of primary monocyte culture technique.

Diagnosis of Rocky Mountain spotted fever was made as early as the fourth day of febrile illness in rhesus monkeys (Macaca mulatta), with a monocyte culture technique that is easily amenable to use in humans. Rickettsia rickettsii were identified by direct immunofluorescent and Gimenez staining of cultures of circulating monocytes from four experimentally infected monkeys, even in the presence of a mild or inapparent disease in three. Levels of rickettsemia were estimated by the plaque-assay technique, and specific antibody titers were determined by complement fixation.