Building black holes: supercomputer cinema.

A new computer code can solve Einstein's equations of general relativity for the dynamical evolution of a relativistic star cluster. The cluster may contain a large number of stars that move in a strong gravitational field at speeds approaching the speed of light. Unstable star clusters undergo catastrophic collapse to black holes. The collapse of an unstable cluster to a supermassive black hole at the center of a galaxy may explain the origin of quasars and active galactic nuclei. By means of a supercomputer simulation and color graphics, the whole process can be viewed in real time on a movie screen.

Intensity Dependence of the Fluorescence Lifetime of in vivo Chlorophyll Excited by a Picosecond Light Pulse.

New data on intensity-dependent lifetimes indicate that all previous in vivo fluorescence studies of chlorophyll by picosecond techniquies must be reinterpreted. Anomalously short lifetimes result from high-intensity effects due to exciton-excition annihilation processes. Measurements in Chlorella pyrenoidosa with single-pulse, low-intensity excitation indicate a longer "true" lifetime of 650 +/- 150 picoseconds.

Picosecond and microsecond pulse laser studies of exciton quenching and exciton distribution in spinach chloroplasts at low temperatures.

Studies of the fluorescence quantum yield and decay times, determined at the emission maxima of 685 and 735 nm, using picosecond laser pulses for excitation, indicate that the pigments which are responsible for the 735 nm emission derive their energy by transfer of singlet excitons from the light-harvesting pigments and not by direct absorption of photons. Microsecond pulse laser studies of the fluorescence quantum yields at these two fluorescence wavelengths indicate that long lived quenchers (most probably triplet states), which quench singlet excitions, accumulate preferentially within the long wavelength pigment system which gives rise to the 735 nm emission band.

Fluorescence lifetimes of alpha- and beta-carotenes.

The fluorescence lifetimes of alpha- and beta-carotenes are both measured by a streak camera technique to be 55 plus or minus 10 ps at a concentration of 6 times 10- minus2 M in chloroform. Carotenes are present in chloroplasts at approximately this concentration.

Frequency of low level bacteremia in infants from birth to two months of age.

BACKGROUND: The frequency of low level bacteremia (< or = 10 colony-forming units/ml) in infants from birth to 2 months of age and the optimal volume of blood and number of blood cultures to be collected have not been well-documented. During 1991 guidelines at this hospital for collection of blood for culture from these infants were revised. METHODS: Blood from each infant with suspected bacteremia was usually inoculated into an Isolator 1.5 Microbial Tube (1.5 ml of blood) and a bottle of anaerobic broth (0.5 to 3.0 ml of blood). The use of a second Isolator tube and the total blood volume recommended for culture (2 to 6 ml) depended on the weight and total blood volume of each infant. RESULTS: Forty-four bacterial pathogens were recovered from the blood of 40 (2.5%) of 1589 infants. Of 34 infants from whose blood the concentration of pathogens could be determined, 23 (68%) had low level bacteremia. Of 50 isolates of pathogens recovered from Isolator cultures, 32 (64%) were detected in counts of < or = 10 colony-forming units/ml. When 2 or 3 blood culture devices were inoculated with a total of 2 to 6 ml of blood from each infant, significantly more cases of bacteremia were detected (34 (3.0%) of 1126 infants had positive blood cultures) than when only one culture device containing < or = 1.5 ml of blood was used (2 (0.5%) of 398 infants had positive blood cultures; P = 0.008). However, when 4 or more culture devices were inoculated with a total of > 6 ml of blood from each infant (5 (7.7%) of 65 infants had positive blood cultures), the difference in recovery of pathogens compared with the culturing of from 2 to 6 ml of blood per infant was not significant (P = 0.089). CONCLUSIONS: Low level bacteremia was common in our infants' patient population. The culturing of up to 6 ml of blood which represented up to 4.5% of an infant's total blood volume was required for detection of the pathogens.

Foreign bodies in small arteries after use of an infusion microcatheter.

Over a 31-month period, we performed four neurointerventional procedures after which unexpected foreign bodies were noted in multiple arteries. All four procedures had in common the use of Fastracker-18 infusion microcatheters. Histologically, the intravascular debris looked strikingly similar to the hydrophilic coating on the catheter. An in vitro test mimicking clinical use of the microcatheter revealed that the hydrophilic coating can separate from the catheter. Until the coating is refined to make it more resistant to stripping, it may be advisable to reduce the amount of back-and-forth movement of these microcatheters if they have been positioned through guide catheters with small inner diameters and angled tips.

Stress management in medical education: a review of the literature.

PURPOSE: To review systematically clinical studies providing empirical data on stress-management programs in medical training. METHOD: The authors searched Medline and PSYCHINFO from 1966 to 1999. Studies were included if they evaluated stress-management programs for medical trainees (medical students, interns, or residents); reported empirical data; and had been conducted at allopathic medical schools. RESULTS: Although the search yielded over 600 articles discussing the importance of addressing the stress of medical education, only 24 studies reported intervention programs, and only six of those used rigorous scientific method. Results revealed that medical trainees participating in stress-management programs demonstrated (1) improved immunologic functioning, (2) decreases in depression and anxiety, (3) increased spirituality and empathy, (4) enhanced knowledge of alternative therapies for future referrals, (5) improved knowledge of the effects of stress, (6) greater use of positive coping skills, and (7) the ability to resolve role conflicts. Despite these promising results, the studies had many limitations. CONCLUSION: The following considerations should be incorporated into future research: (1) rigorous study design, including randomization and control (comparison) groups, (2) measurement of moderator variables to determine which intervention works best for whom, (3) specificity of outcome measures, and (4) follow-up assessment, including effectiveness of future patient care.

The construct of control in mind-body medicine: implications for healthcare.

Research suggests that one of the principal reasons patients are attracted to alternative medicine is that they find many of these therapies more congruent with their philosophical orientation toward health. Many mind-body approaches, which are some of the most frequently used classifications of complementary and alternative therapies, grow out of research demonstrating the important role of psychological factors in treating and preventing illness. This article reviews research on one such factor--control--and its importance in health. Studies demonstrating the following are highlighted: (1) illness frequently results in feelings of loss of control; (2) gaining a sense of control can help patients to cope with illness; (3) whereas control may influence physiological function and health outcomes, the amount of active control we can exercise over physical functioning and health is limited; and (4) it is important to match control strategies to patient control styles and preferences. The implications of mind-body studies are also discussed.

Antenatal diagnosis of epignathus with neonatal survival. A case report.

Antenatal diagnosis was made of bilobed epignathus arising from the fetal palate. The fetus survived. Antenatal recognition of this malformation allows adequate preparation of the neonatal and surgical teams to ensure optimal fetal survival.

Sonographic evaluation of interdigital neuromas.

Fifty surgical patients with symptoms suggestive of Morton's neuroma underwent preoperative ultrasound examination of the forefoot using a 7.5 MHz transducer. Fifty-five neuromas were excised. Of these, one neuroma had a ganglion associated with it and five neuromas were recurrent. Four feet had adjacent neuromas. Ultrasound accurately predicted the presence, location and size of the neuromas in 98% of the cases. There were no false positives. In all cases in which a neuroma was predicted by ultrasound, it was confirmed grossly at the time of surgery and later by histological exams. We conclude that ultrasound is an accurate technique in the diagnosis of interdigital neuromas.

Ultrasonographic diagnosis of recurrence after excision of an interdigital neuroma.

We retrospectively reviewed the records of 20 patients (21 feet) with previous interdigital neuroma resections and symptoms suggestive for, but not diagnostic of, recurrent neuroma. Sonography was performed when clinical findings supplemented by local anesthetic block did not conclusively confirm the presence of recurrent neuroma. Studies performed in 13 patients (14 feet) were positive for recurrent neuromas. Three studies were indeterminate. The remaining four studies were negative for recurrent neuroma. The ultrasound studies were performed at an average of 19.2 months (range, 2-82 months) after the resection. Nine patients with 11 previous interdigital neuromas underwent ultrasonographic examination of the forefoot and subsequent revision neuroma resection. At surgery, gross and histologic findings were consistent with recurrent neuroma in 10 of 11 cases; one patient was found to have metatarsal-phalangeal synovitis. Ultrasonography appears to be a useful means for confirming neuroma recurrence in patients with symptoms after interdigital neurectomy when the diagnosis is not clear on physical examination.

Intentional systemic mindfulness: an integrative model for self-regulation and health.

Self-regulation is the process whereby systems maintain stability of functioning and adaptability to change. Self-regulation is based on feedback loops which can be enhanced through attention. All self-regulation techniques, therefore, involve the cultivation of attention. However, the intention with which attention is directed may be crucial. In this paper, we explore intentional systemic mindfulness a model that explicitly introduces intention into self-regulation theory and practice. Intention as defined by this model is composed of the context of attention-systemic perspectives - and the quality of attention - mindfulness qualities. Intentional systemic mindfulness addresses both "why" (systemic perspectives) and "how" (mindfulness qualities) one directs attention, which may promote healing on multiple levels. Directions for research and implications for multiple levels of integrative health are considered.