Pulsed triple frequency modulation for frequency stabilization and control of two lasers to an optical cavity.

We present a method to stabilize two lasers to an optical cavity using pulsed triple frequency modulation. The setup allows simultaneous Pound-Drever-Hall stabilization, as well as independent frequency control, while removing interference terms that limit the frequency scan range and allowing for smaller modulation depths. A review of single, dual, and triple frequency modulation is also presented in addition to a discussion of how to effectively turn pulsed triple frequency modulation into independent dual frequency modulation for each laser. This method would increase the scan range to half the free spectral range.

Testing Quantum Electrodynamics in the Lowest Singlet State of Neutral Beryllium-9.

We report spectroscopic results on the 2s2p^{1}P_{1} state in neutral atomic beryllium-9. The absolute frequency for the center of gravity is determined to be 42 565.4501(13) cm^{-1}, a factor of 130 more precise than the previous experimental measurement. The result is in agreement with and a factor of 8 more precise than the current best theoretical estimate of 42 565.441(11) cm^{-1}, which was calculated including the effects of quantum electrodynamics. Because of the large natural linewidth of the transition, the hyperfine constants were not able to be extracted to high precision.

Factor analysis of bowel symptoms in US and Italian populations.

BACKGROUND AND AIMS: Functional gastrointestinal disorders are diagnosed by the presence of a characteristic set of symptoms. Aims of this study were to validate the Rome symptom criteria by factor analysis and to determine whether symptoms cluster in the same way in different cultures. METHODS: One thousand forty-one gastroenterology clinic patients in the US (response rate 53%) and 228 family members accompanying clinic patients in Italy (84%) completed a previously validated symptom questionnaire. Factor analysis identified clusters of symptoms which are highly correlated with each other, and these were compared to the Rome diagnostic criteria. RESULTS: In the US, 13 factors were identified. The irritable bowel factor was composed of three core symptoms corresponding to the Rome II classification system. Two dyspepsia factors were identified which correspond to the ulcer- and motility-like subtypes proposed in the Rome I classification system. All symptoms of constipation formed a single cluster as proposed in the Rome II classification system. Symptom clusters in the US agreed well with symptom clusters identified in Italian subjects. CONCLUSIONS: Empirically derived symptom clusters agree in most respects with the Rome II classification system and support their validity. These symptom clusters are independent of cultural differences in diet and behaviour.

Hospitalist programs: are they good for your practice?

With the changes brought about in health care delivery by the growth of Managed Care, the attractions of hospitalist programs are becoming increasingly evident. As the programs have grown in usage, and program models have evolved from mandatory to voluntary, primary care physicians (PCPs) and independent practice organizations (IPAs) have begun to recognize their positive impact on their practices, from both financial and logistic perspectives, as well from those of patient care. This article discusses that effect and reviews the procedures and ramifications of one of the newer program models. Quality of patient care and the provision of successful outcomes via clinical guidelines are addressed as indications of successful hospitalist programs.

Development of an interdisciplinary, telephone-based care program.

An interdisciplinary, telephone-based care program at a Veterans Affairs medical center (VAMC) is described. Patients telephoning the Oklahoma City VAMC complained that they were transferred multiple times and that they had difficulty contacting their provider between scheduled visits. Some went to the walk-in urgent care clinic with nonurgent problems. The average waiting time in the clinic exceeded three hours. An interdisciplinary, telephone-based care program was begun in 1995 to allow efficient problem resolution over the telephone; provide clinical consultations, interventions, and referrals as necessary; and reduce use of the urgent care clinic for nonurgent problems. A team consisting of a patient service representative, a pharmacist, and a nurse was established to handle calls. Policies and procedures were designed to respond appropriately to patients' problems and document the telephone "visits." The pharmacist was given practice privileges, including prescribing authority. A questionnaire indicated patient satisfaction with the new service. Mean waiting times in the urgent care clinic were reduced to less than two hours, and an estimated annual net cost avoidance of $677,671 was achieved by the program's averting unnecessary visits to the urgent care clinic. An interdisciplinary, telephone-based care program at a VAMC successfully responded to patients' concerns, improved their access to care, and conserved urgent care resources.

Centers for Disease Control performance evaluation program in bacteriology: 1980 to 1985 review.

This report presents a summary and analysis of data from the Centers for Disease Control performance evaluation program in bacteriology for the 6-year period 1980 to 1985. During this period, the number of laboratories enrolled in the program ranged from about 750 to 1,000. Identification results reported by participating laboratories for representative species of six major groups of bacteria were placed into five response categories that were based on the level and accuracy of the identifications. Data on the performance of participants with bacterial groups and performance with selected species within each major group were analyzed. Overall, participants experienced the least difficulty in identifying species or serogroups of members of the gram-positive and gram-negative cocci. Participants encountered greater difficulties with anaerobes, gram-positive bacilli, and miscellaneous gram-negative bacteria. Identification of members of the family Enterobacteriaceae was of moderate difficulty. Problems in identifying certain bacterial species were probably related to a number of factors such as the characteristics of the species, its frequency of occurrence, the state of technology available for identification, and the state of proficiency and quality control in individual laboratories at the time of testing. Examples are given of improvements over time in the identification of certain bacterial species. Laboratories participating in an external proficiency testing program should take full advantage of the benefits of participation by instituting measures to correct testing deficiencies identified by the program.

Relationship between performance in three of the Centers for Disease Control microbiology proficiency testing programs and the number of actual patient specimens tested by participating laboratories.

The performance of laboratories enrolled in three of the Centers for Disease Control microbiology performance evaluation programs was studied in relation to the number of actual patient specimens tested by the laboratories. Laboratories were grouped according to the number of specimens tested weekly to compare performance among the groups. Results of the study showed that laboratories, as a group, that tested large numbers of specimens performed better than laboratories that tested small numbers. The infrequency of performing certain tests or identifying certain microbial species can be an important factor in laboratory error. One strategy for laboratories that cannot resolve internal problems associated with low testing volumes would be to limit their testing to procedures that are done well.

Preparation and stability of freeze-dried Neisseria gonorrhoeae cultures used for external quality control.

In 1976, the Center for Disease Control initiated an external quality control program for the isolation and identification of Neisseria gonorrhoeae. This program required microbial samples of sufficient stability for shipment to laboratories throughout the United States. The Centers for Disease Control undertook studies to determine the most appropriate media for the propagation of strains for freeze-drying, the cell-suspending media that would afford protection during and after freeze-drying, the most favorable growth conditions, the proper times and methods for harvesting cells, the appropriate lyophilization conditions, the critical residual moisture content, and the stability of samples. These studies resulted in the development of methods for preparing and testing freeze-dried samples suitable for shipment.

Five years of experience with a national external quality control program for the culture and identification of Neisseria gonorrhoeae.

In response to a need for monitoring the proficiency of public health laboratories in isolating and identifying Neisseria gonorrhoeae, a national external quality control program was developed. Essentially, three types of freeze-dried samples, representing different levels of challenge for identification, were sent to laboratories for testing. The quality of the samples was confirmed by external reference laboratories, and stability of the samples was confirmed by thermal degradation tests before the samples were sent to laboratories enrolled in the program. By analyzing laboratory results, we identified common errors and chronic problems in testing samples. As a group, laboratories testing small numbers of actual patient specimens did not perform as well in the program as did laboratories testing large numbers of specimens; however, the performance of laboratories testing small numbers of specimens improved over time. Overall, laboratories experienced the most difficulty with samples containing N. gonorrhoeae mixed with other microbial species. Laboratories that performed confirmatory tests committed fewer errors than did laboratories that performed presumptive tests only, but the failure to use pure cultures of gonococci for inoculation of cystine tryptic digest agar appeared to be a chronic problem in confirmatory carbohydrate testing. A review of the use of different plating media and confirmatory tests showed that the use of certain media and tests changed over time.