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J R Patterson

Publications and source records attributed to J R Patterson.

At least 73 records · Page 4Linked to original sources
PubMed2001

Single-wall carbon nanotubes under high pressures to 62 GPa studied using designer diamond anvils.

Single-wall carbon nanotube samples were studied under high pressures to 62 GPa using designer diamond anvils with buried electrical microprobes that allowed for monitoring of the four-probe electrical resistance at elevated pressure. After initial densification, the electrical resistance shows a steady increase from 3 to 42 GPa, followed by a sharp rise above 42 GPa. This sharp rise in electrical resistance at high pressures is attributed to opening of an energy band gap with compression. Nanoindentation hardness measurements on the pressure-treated carbon nanotube samples gave a hardness value of 0.50 +/- 0.03 GPa. This hardness value is approximately 2 orders of magnitude lower than the amorphous carbon phase produced in fullerenes under similar conditions. Therefore, the pressure treatment of single-wall carbon nanotubes to 62 GPa did not produce a superhard carbon phase.

Crystallization↗
PubMed2000

Electrical and mechanical properties of C70 fullerene and graphite under high pressures studied using designer diamond anvils.

We compare electrical and mechanical properties of C70 fullerene with high purity graphite to 48 GPa at room temperature using designer diamond anvils with embedded electrical microprobes. The electrical resistance of C70 shows a minimum at 20 GPa with transformation to an amorphous insulating phase complete above 35 GPa, while graphite remains conducting. Nanoindentation shows hardness values 220 times larger for the pressure quenched amorphous phase than for similarly treated graphite. Our studies establish that the amorphous carbon phase produced from C70 has unique properties not attainable from graphite.

Journal Article↗
PubMed2000

Study of charmless hadronic B meson decays to pseudoscalar-vector final states.

We report results of searches for charmless hadronic B meson decays to pseudoscalar( pi(+/-), K+/-, pi(0), or K(0)(S))-vector( rho, K(*), or omega) final states. By using 9.7x10(6) BB pairs collected with the CLEO detector, we report the first observation of B(-)--->pi(-)rho(0), B(0)-->pi(+/-)rho(-/+), and B(-)-->pi(-)omega, which are expected to be dominated by hadronic b-->u transitions. The measured branching fractions are (10.4(+3.3)(-3.4)+/-2.1)x10(-6), (27.6(+8.4)(-7.4)+/-4.2)x10(-6), and (11.3(+3.3)(-2.9)+/-1. 4)x10(-6), respectively. Branching fraction upper limits are set for all of the other decay modes investigated.

Journal Article↗
PubMed1996

Increased intraluminal pressure induces DNA synthesis and c-fos expression in perfused rat aorta.

The molecular mechanisms responsible for the vascular hypertrophy observed in the arteries of hypertensive subjects are poorly understood. In this study, we tested the hypothesis that an increase in intraluminal pressure could by itself induce some of the vascular changes associated with hypertension, such as increased DNA synthesis and c-fos expression. We perfused rat thoracic aortae at different pressures for up to 4 h. The perfusion system consisted of a peristaltic pump and a closed circuit of plastic tubing connected to a culture media bottle where rat thoracic aortae were placed. After a 30 min equilibration period at 20 mm Hg, the perfusion pressure was adjusted to "normotensive levels" (132 +/- 3/59 +/- 4 mm Hg) or "hypertensive levels" (204 +/- 5/74 +/- 8 mm Hg). 3H-Thymidine was added at this time. After 4 h, the arteries were removed from the apparatus. Tunica media and adventitia were separated and processed for scintillation counting. 3H-Thymidine incorporation was 39% higher in the "hypertensive" than in the "normotensive" arteries. In separate experiments, after a 20 min equilibration period, the arteries were perfused for an additional 30 min at 50/10, 100/35, or 150/50 mm Hg. After being removed from the perfusion apparatus, the arteries were homogenized and total RNA was isolated. c-fos Expression was analyzed by Northern blot. c-fos Expression corresponded directly with the perfusion pressure. The highest levels of c-fos expression were detected in the arteries exposed to the highest pressures. These findings support the hypothesis that hemodynamic and/or mechanical factors can influence cell growth and function.

Animals↗
PubMed1995

Physicians as patients. Choices regarding their own resuscitation.

BACKGROUND: Attitudes toward cardiopulmonary resuscitation have changed considerably during the last 30 years. Although physicians are routinely involved in the decision making about cardiopulmonary resuscitation for their patients, little is known about their collective preferences regarding it for themselves. METHODS: A questionnaire was distributed at an internal medicine primary care review course at an urban community hospital. Of the 111 physicians registered at the meeting, 72 (65%) completed the questionnaire and serve as the basis for the results. Physicians were asked if they would want cardiopulmonary resuscitation for themselves in the presence of an acute myocardial infarction, Alzheimer's disease, and nine other advanced chronic diseases at the projected ages of 40, 60, and 80 years. RESULTS: At all projected ages, physicians' desire for cardiopulmonary resuscitation with any advanced chronic disease was significantly less than with an acute myocardial infarction (P < or = .000001 except for rheumatoid arthritis). Fewer physicians wanted cardiopulmonary resuscitation at age 80 years than at 40 years for any disease (P < or = .002). The results did not differ when analyzed by respondents' age, gender, or primary care specialty, or the size of the community in which they practiced. CONCLUSIONS: The results of this initial survey indicate that most physicians would not want cardiopulmonary resuscitation with a variety of underlying chronic diseases and corresponding functional impairments--particularly with advancing age. Conversely, with an acute myocardial infarction, all physicians surveyed would desire cardiopulmonary resuscitation at age 40 years, and many would continue to desire it with advancing age.

Acute Disease↗
PubMed1995

Hypothermia induced by laparoscopic insufflation. A randomized study in a pig model.

Hypothermia is a common postsurgical problem, yet information documenting the impact of laparoscopy on perioperative heat balance is scarce. This paper quantifies the changes in core temperature over a 3-h period of high-flow CO2 insufflation in a randomized, controlled trial of six pigs. Each animal was anesthetized and studied on three occasions under standardized conditions, acting as its own control via insufflation with no gas compared with insufflation by cold gas and warmed gas. Insufflation of CO2 gas at high-flow rates over a prolonged period of time results in a significant fall in core temperature. The provision of warmed rather than cold insufflated gas confers no protection against changes in core temperature during laparoscopic surgery due to the small amount of heat required to warm the gas to body temperature. A much greater effect is the latent heat required to saturate the insufflated gas. Most of the hypothermic effect is due to this, and could be minimized by humidifying the flow.

Animals↗
PubMed1992

Survey and risk assessment of radium contamination in a historic desk.

For many years the Physics Department of The University of Adelaide has owned a fine cedar desk which dates from before 1900. It was used by professors, including Sir Kerr Grant, for many years and probably Sir William Bragg. In April 1991, approximately 80 kBq of radium contamination was found in parts of the desk. Because of concern for the health of those who had used the desk, a thorough study was made of the nature and extent of the contamination and the risks to health from radon and from ingesting some of the radioactive material from contact with articles such as pencils, stamps and envelopes kept in the drawer. The risks have been shown to be small compared to other acceptable risks in modern society. The desk has been decontaminated and restored.

Australia↗
PubMed1988

Survey of chloramphenicol residues in diseased swine.

Tissue samples from 279 hogs suspected of having received antibiotic treatment were collected at federally-inspected abattoirs and submitted for chloramphenicol residue analysis during August and September 1984. Injection sites (when present), kidneys or muscle samples were tested by one of two gas chromatographic methods. Kidney samples were also tested at the abattoirs by the Swab Test On Premises. Thirty-one animals (11%) were found with detectable levels ranging from 1 part per billion to 5727 ppb. Highest levels were found at the injection sites, while levels in muscle tissue did not exceed 500 ppb. None of the kidneys from animals found to contain chloramphenicol residues produced a positive Swab Test On Premises result attributable to the presence of chloramphenicol. Twelve kidneys from animals free of chloramphenicol residues produced positive Swab Test On Premises results. Of these, five contained penicillin or streptomycin, but antibiotic residues were not detected in the remaining seven. In addition to the samples collected for this survey, samples from eight hogs representing a herd which had been treated for pneumonia were submitted by an abattoir in Manitoba in November 1984. Chloramphenicol levels in these animals ranged from 0.1 to 73 parts per million in the injection sites, and from 0.04 to 21 ppm in the muscle tissues. The survey data indicated that there were a significant number of animals reaching the abattoirs with detectable chloramphenicol residues, and that the Swab Test On Premises procedure was ineffective in detecting these animals.

Abattoirs↗
PubMed1984

Detection and occurrence of pentachlorophenol residues in chicken liver and fat.

A method for the detection of pentachlorophenol (PCP) residues in chicken liver and fat is presented. A detection limit of 0.002 mg/kg was achieved. Recoveries from liver and fat were in the range 82-88% and 95-97%, respectively. Low level residues of PCP were found in all 1072 liver and 723 fat samples. These levels were less than 0.010 mg/kg in 92.7% of the fat and 75.6% of the livers. Only 0.75% of the liver samples had PCP levels greater than 0.1 mg/kg. None of the more toxic impurities of PCP were detected in the chicken tissues.

Adipose Tissue↗
PubMed1978

Interstitial pneumonia from mitomycin.

Pulmonary disease has been associated with several chemotherapeutic agents but has not been reported in patients receiving the alkylating agent mitomycin (Mutamycin). We describe here the cases of three patients who developed interstitial pneumonia while receiving mitomycin therapy. Their clinical features including dyspnea, cough, and occasionally fever; reticular infiltrates were seen on chest roentgenogram. Histologically, diffuse alveolar septal edema, mononuclear-cell interstitial infiltrates, hypertrophy of alveolar lining cells, and alveolar septal collagen deposition were characteristic. Treatment with corticosteroids was associated with a rapid therapeutic response in all three patients.

Female↗