Ramp compression of diamond to five terapascals.

The recent discovery of more than a thousand planets outside our Solar System, together with the significant push to achieve inertially confined fusion in the laboratory, has prompted a renewed interest in how dense matter behaves at millions to billions of atmospheres of pressure. The theoretical description of such electron-degenerate matter has matured since the early quantum statistical model of Thomas and Fermi, and now suggests that new complexities can emerge at pressures where core electrons (not only valence electrons) influence the structure and bonding of matter. Recent developments in shock-free dynamic (ramp) compression now allow laboratory access to this dense matter regime. Here we describe ramp-compression measurements for diamond, achieving 3.7-fold compression at a peak pressure of 5 terapascals (equivalent to 50 million atmospheres). These equation-of-state data can now be compared to first-principles density functional calculations and theories long used to describe matter present in the interiors of giant planets, in stars, and in inertial-confinement fusion experiments. Our data also provide new constraints on mass-radius relationships for carbon-rich planets.

Study of exclusive charmless semileptonic B decays and |Vub|.

We study semileptonic B decay to the exclusive charmless states pi, rho/omega, eta, and eta;{'} using the 16 fb(-1) CLEO Upsilon(4S) data sample. We find B(B0-->pi-l+nu)=(1.37+/-0.15stat+/-0.11sys)x10(-4) and B(B0-->rho-l+nu)=(2.93+/-0.37stat+/-0.37sys)x10(-4) and find evidence for B+-->eta'l+nu, with B(B+-->eta'l+nu)=(2.66+/-0.80stat+/-0.56sys)x10(-4). From our B-->pilnu rate for q2>16 GeV2 and lattice QCD, we find |Vub|=(3.6+/0.4stat+/0.2syst-0.4thy+0.6)x10(-3) [corrected]

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.

Preferred surgical treatment for alveolar cell carcinoma.

An analysis of our experience with 48 patients having bronchiolar or alveolar cell carcinoma is reported. The remarkable biological variability of this peripheral tumor has important surgical implications. Basically, two dominant clinical presentations occur. In the less common diffuse or multinodular form, prolonged survival is infrequent regardless of the therapeutic approach. Often these patients die from respiratory compromise due to the tumor itself. In the more common localized or solitary form the prognosis for cure is good, approximating 47% or higher. Based on the material presented, lobectomy is the preferred method of surgical treatment. In patients manifesting multinodular disease, surgical resection rarely seems warranted. The concept of preserving pulmonary tissue is stressed.

An indeterministic Monte Carlo technique for fast time of flight photon transport through optically thick turbid media.

A time-resolved indeterministic Monte Carlo (IMC) simulation technique is proposed for the efficient construction of the early part of the temporal point spread function (TPSF) of visible or near infrared photons transmitted through an optically thick scattering medium. By assuming a detected photon is a superposition of photon components, the photon is repropagated from a point in the original path where a significant delay in forward propagation occurred. A weight is then associated with each subsequently detected photon to compensate for shorter components. The technique is shown to reduce the computation time by a factor of at least 4 when simulating the sub-200 picosecond region of the TPSF and hence provides a useful tool for analysis of single photon detection in transillumination imaging.

First photon detection in time-resolved transillumination imaging: a theoretical evaluation.

First photon detection, as a special case of time-resolved transillumination imaging, is studied through the derivation of the temporal probability density function (pdf) for the first arriving photon. The pdf for different laser intensities, media and second and later arriving photons were generated. The arrival time of the first detected photon reduced as the laser power increased and also when the scattering and absorption coefficients decreased. The pdf for an imbedded totally absorbing 3 mm inhomogeneity may be distinguished from the pdf of a homogeneous turbid medium similar to that of human breast in dimensions and optical properties.

Spatial resolution in fast time-resolved transillumination imaging: an indeterministic Monte Carlo approach.

The spatial resolution achievable in time-resolved optical transillumination imaging through a turbid (scattering and absorbing) medium has been reassessed theoretically. The temporal point spread function was constructed assuming a delta function input pulse, a approximately 50 mm thick medium and a small detector with zero risetime. Temporal profiles were derived from an indeterministic Monte Carlo simulation for different time scales. From the temporal point spread function (TPSF), an analytic edge response function from which the spatial resolution was determined was derived. Previous analytical methods for determining the spatial resolution are approximations for very short flight times (sub-100 ps time region). The results show that a spatial resolution of about two millimetres is possible under ideal signal-to-noise ratio conditions and with detector gate times of the order of ten picoseconds. If this predicted spatial resolution can be achieved in an imaging system, it may be possible to improve the diagnosis of breast tumours.

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.

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.

Determination of flunixin residues in bovine muscle tissue by liquid chromatography with UV detection.

A new and sensitive liquid chromatography-ultra violet method with a detection limit of 6 ng/g (ppb) and a limit of quantification of 15 ng/g was developed for the determination of flunixin residues in bovine muscle tissue. Flunixin in homogenized animal tissue was extracted with acetonitrile after enzyme digestion. The tissue digest (extract) was then cleaned up on a solid-phase extraction cartridge and eluted with acidified hexane. After the eluate was evaporated to dryness under nitrogen at 55 degrees C, the residue was reconstituted in 1 mL mobile phase solution and analyzed by reversed-phase gradient chromatography with UV detection at 285 nm. The method was then applied in a survey study of slaughter animals to determine whether flunixin is being used in an off-label manner for veal and beef production in Canada.

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.

Occurrence of sulfa drug residues in canadian pork liver.

Sulfonamide residues in the livers of wholesome carcasses of Canadian pork were monitored over the six year period ending March 31, 1985. The annual rate of violative residues decreased from 9.92% to 2.75% over the course of the six years. At present the incidence of violation in the livers is 2.35% and there is no significant difference within the various regions of Canada. This would result in a muscle violative rate of 0.8%.The only sulfonamide found at violative levels was sulfamethazine. All violative samples were within the range 0.11-4.00 ppm. Over the period of the survey the incidence of violations at all levels decreased. Violations at higher levels decreased most rapidly resulting in a continuous reduction of the mean level in violative samples.

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.

Demonstration of a 13-keV Kr K-shell x-ray source at the National Ignition Facility.

We report 3% conversion efficiency of laser energy into Kr K-shell (≈13 keV) radiation, consistent with theoretical predictions. This is ≈10× greater than previous work. The emission was produced from a 4.1-mm-diameter, 4-mm-tall gas pipe target filled with 1.2 or 1.5 atm of Kr gas. 160 of the National Ignition Facility laser beams deposited ≈700 kJ of 3ω light into the target in an ≈140 TW, 5.0-ns-duration square pulse. The Dante diagnostics measured ≈5 TW into 4π solid angle of ≥12 keV x rays for ≈4 ns, which includes both continuum emission and flux in the Kr He_{α} line at 13 keV.

A Langmuir probe diagnostic for time-of-flight measurements of transient plasmas produced by high-energy laser ablation.

We discuss here the development of a Langmuir probe (LP) diagnostic to examine high-density, high-temperature inhomogeneous plasmas such as those that can be created at the University of Rochester's Laboratory for Laser Energetics OMEGA facility. We have configured our diagnostic to examine the velocity of the plasma expanding from the target. We observe velocities of approximately 16-17 cm/µs, with individual LP currents displaying complex structures, perhaps due to the multiple atomic species and ionization states that exist.

Source geometric considerations for OMEGA Dante measurements.

The Dante is a 15 channel filtered diode array which is installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The system yields the spectrally and temporally resolved radiation flux from 50 eV to 10 keV from various targets (i.e., Hohlraum, gas pipes, etc.). The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and an unfold algorithm applied to the recorded voltages from each channel. The unfold algorithm assumes an emitting source that is spatially uniform and has a constant area as a function of photon energy. The emitting x-ray source is usually considered to be the laser entrance hole (LEH) of a given diameter for Hohlraum type targets or the effective wall area of high conversion efficiency K-shell type targets. This assumption can be problematic for several reasons. High intensity regions or "hot spots" in the x-ray are observed where the drive laser beams strike the target. The "hot spots" create non-uniform emission seen by the Dante. Additionally, thinned walled (50 µm) low-Z targets (C(22)H(10)N(2)O(5)) have an energy dependent source size since the target's walls will be fully opaque for low energies (E < 2-3 keV) yet fully transmissive at higher energies. Determining accurate yields can be challenging for these types of targets. Discussion and some analysis will be presented.

Single-mode fiber, velocity interferometry.

In this paper, we describe a velocity interferometer system based entirely on single-mode fiber optics. This paper includes a description of principles used in developing the single-mode velocity interferometry system (SMV). The SMV design is based on polarization-insensitive components. Polarization adjusters are included to eliminate the effects of residual birefringence and polarization dependent losses in the interferometers. Characterization measurements and calibration methods needed for data analysis and a method of data analysis are described. Calibration is performed directly using tunable lasers. During development, we demonstrated its operation using exploding-foil bridge-wire fliers up to 200 m/s. In a final test, we demonstrated the SMV in a gas gun experiment up to 1.2 km/sec. As a basis for comparison in the gas gun experiment, we used another velocimetry technique that is also based on single-mode fiber optics: photonic Doppler velocimetry (PDV). For the gas gun experiment, we split the light returned from a single target spot and performed a direct comparison of the homodyne (SMV) and heterodyne (PDV) techniques concurrently. The two techniques had a negligible mean difference and a 1.5% standard deviation in the one-dimensional shock zone. Within one interferometer delay time after a sudden Doppler shift, a SMV unencumbered by multimode-fiber dispersion exhibits two color beats. These beats have the same period as PDV beats-this interference occurs between the "recently" shifted and "formerly unshifted" paths within the interferometer. We believe that recognizing this identity between homodyne and heterodyne beats is novel in the shock-physics field. SMV includes the conveniences of optical fiber, while removing the time resolution limitations associated with the multimode delivery fiber.