X-ray diffraction from nonperiodic layered structures with correlations: analytical calculation and experiment on mixed Aurivillius films.

X-ray diffraction from films consisting of layers with different thicknesses, structures and chemical contents is analysed. The disorder is described by probabilities for different sequences of layers. Closed analytical expressions for the diffracted X-ray intensity are obtained when the layers form a stationary Markov chain. The proposed model is applied to the diffraction data from epitaxial sodium bismuth titanate thin films with Aurivillius structure possessing such one-dimensional disorder. In this case, the disorder is caused by a random stacking of three and four perovskite units separated by bismuth oxide interlayers. The results of analytical calculations are in good agreement with the experimental data and indicate that the incorporation of sodium in the Bi(4)Ti(3)O(12) phase causes the formation of a fourth perovskite unit.

Effectiveness of a novel endoscopy training concept.

BACKGROUND AND STUDY AIMS: Training standards in gastrointestinal endoscopy are poorly defined even though different simulators are increasingly used for skills training. In 2001 a new training concept called "GATE--gastroenterological education-training endoscopy" was established, which provides a combination of background theory, video demonstrations, and simulator training. We aimed to evaluate the acceptance and training effect of this training model. METHODS: In total, 98 physicians participating in four training courses were included. Data were collected on baseline characteristics, acceptance (5-point Likert scale), and pre- and post-course knowledge through a structured questionnaire (A-type and Pick-N multiple choice questions). A total of 13 trainees were randomly selected for additional simulator assessment of training effects on manual skills (5-point Likert scale). RESULTS: A total of 78 trainees (80%) provided complete data sets. The evaluation showed a positive acceptance of the training program (value 1 and 2, Likert scale); for example, 88% of participants suggested the inclusion of the GATE course as an obligatory part of endoscopic education. There was a significant improvement in theoretical knowledge in the post-test set compared with the pre-test set (mean 3.27 ±1.30 vs. 1.69 ±1.01 points; P<0.001). The training effect on practical skill showed a significant reduction in time needed for a procedure (445 ±189 s vs. 274 ±129 s; P<0.01). The mean assessment rating for practical skills improved from 3.05 ±0.65 at baseline to 2.52 ±0.59 on Likert scale ( P=0.085). CONCLUSIONS: The integrated GATE training improved theoretical knowledge and manual skill. The GATE courses have been accredited by the German Society of Gastroenterology, underlining the demand for implementing preclinical training courses in endoscopic training.

Quality indicators for the prevention of type 2 diabetes in Europe--IMAGE.

BACKGROUND: The marked increase of type 2 diabetes necessitates active development and implementation of efficient prevention programs. A European level action has been taken by launching the IMAGE project to unify and improve the various prevention management concepts, which currently exist within the EU. This report describes the background and the methods used in the development of the IMAGE project quality indicators for diabetes primary prevention programs. It is targeted to the persons responsible for diabetes prevention at different levels of the health care systems. METHODS: Development of the quality indicators was conducted by a group of specialists representing different professional groups from several European countries. Indicators and measurement recommendations were produced by the expert group in consensus meetings and further developed by combining evidence and expert opinion. RESULTS: The quality indicators were developed for different prevention strategies: population level prevention strategy, screening for high risk, and high risk prevention strategy. Totally, 22 quality indicators were generated. They constitute the minimum level of quality assurance recommended for diabetes prevention programs. In addition, 20 scientific evaluation indicators with measurement standards were produced. These micro level indicators describe measurements, which should be used if evaluation, reporting, and scientific analysis are planned. CONCLUSIONS: We hope that these quality tools together with the IMAGE guidelines will provide a useful tool for improving the quality of diabetes prevention in Europe and make different prevention approaches comparable.

Large coherence area thin-film photonic stop-band lasers.

We demonstrate that the shift of the stop-band position with increasing oblique angle in periodic structures results in a wide transverse exponential field distribution corresponding to strong angular confinement of the radiation. The beam expansion follows an effective diffusive equation depending only upon the spectral mode width. In the presence of gain, the beam cross section is limited only by the size of the gain area. As an example of an active periodic photonic medium, we calculate and measure laser emission from a dye-doped cholesteric liquid crystal film.

Preoperative preparation. Value, perspective, and practice in patient care.

Preanesthesia preparation will continue to stimulate creativity and debate. Strategies for process improvement will take various shapes and require tools previously unfamiliar to many medical managers. At UNC Health System, anesthesiologists currently are committed to the centralized preanesthesia clinic approach used in PreCare. To date, their strategies have been validated by their institutional measures of success: a 0.7% first-case AM work-up rate, a 5% no PreCare visit rate, a 5% consent problem rate, and a 0% rejected specimen rate, with a 43% blood-draw rate for all patients. As their health system expands, however, other strategies and preparation modalities may become necessary. Telemedicine and Internet-dependent processes are appealing in the highly educated and technologically sophisticated marketplace. As the region becomes increasingly urbanized, local employment patterns prevent easy access to services, and functional compromises, such as bypassing PreCare or reliance on telephone or on-line interviews for preparation, may become necessary. The need to expand PreCare in the near future is already evident. As was found during initial planning, process improvement and space planning are enhanced by computer modeling. UNC Health System employed a proprietary animated simulation modeling (ASM) tool, MedModel, (ProModel, Orem, UT), although other techniques exist for the same purpose. Use of ASM as a strategy management tool allowed generation of ideal space-time-personnel scenarios that could expose potential problems before resources and physical restructuring occurred. ASM also can be used to compare data obtained from real-time observations to any reference scenario, including any that looks at economic measures of process, to help refine strategic visions before instituting tactical solutions. Used in this manner, ASM can reveal physical, temporal, personnel, and policy-related factors not otherwise seen as exerting effects on overall preprocedural preparation processes. Coupled with other classic planning techniques, such as time-motion studies, modified Delphi techniques, customer satisfaction surveys, benchmarking studies, and financial analysis and growth projections, ASM has helped enhance total quality management efforts in PreCare and other planning projects at UNC Health System. Other researchers have used other simulation techniques to assess clinic functions. Operational challenges that exist in preanesthesia preparation clinics place these clinics on the same level as other kinds of medical service clinics. The lessons learned in most clinic settings may be applied in a cross-wise manner to the preanesthesia clinic. Dexter contends that efficient delivery of care that respects patients' time and needs does more than assist the procedural preparation process; it also supports the physician's ethical obligation to the patient to give the best possible care. Documenting patient medical information, education efforts, and maintaining the medical-legal integrity of the preanesthesia preparation materials is another area of increasing concern and research. When hand-held computers capable of linking by way of infrared technologies or that use rented downloadable software to run specific applications become commonly used, the complexity of ensuring privacy will grow. The complexity, however, will not be insurmountable. Privacy problems exist in any information management system, whether paper-based (i.e., reducing redundant forms, eliminating indiscriminant photocopying of records), electronic-based (i.e., encryption, server access, system failure), or both. Electronic conveyance of medical information faces more legal and economic than technical hurdles. The penetration in US households of Internet services presently is less than 40%, whereas the penetration of personal computers is just over 50%. These figures are compared with penetration of corded telephones, televisions, and radios at levels greater tha

Tracheal extubation of deeply anesthetized pediatric patients: a comparison of isoflurane and sevoflurane.

UNLABELLED: We studied the emergence characteristics of unpremedicated children tracheally extubated while deeply anesthetized ("deep extubation") with isoflurane or sevoflurane. Forty children were assigned to one of two groups, Group I or Group S. At the end of the operation, Group I patients were extubated while breathing 1.5 times the minimum alveolar anesthetic concentration (MAC) of isoflurane. Group S patients were tracheally extubated while breathing 1.5 times the MAC of sevoflurane. Recovery characteristics and complications were noted. Group S patients were arousable sooner than Group I patients (10.1 + 6.5 vs 16.3 + 9.9 min). Later arousal scores and times to discharge were the same. There were no serious complications in either group. Breath-holding was more common in Group I. We conclude that the overall incidence of airway problems and desaturation episodes was similar between groups. Emergency delirium was common in both groups (32% overall: 40% for Group I, 25% for Group S). IMPLICATIONS: Deep extubation of children can be safely performed with either isoflurane or sevoflurane. After deep tracheal extubation, airway problems occur but are easily managed. Return to an arousable state occurred more quickly with sevoflurane, although time to meeting discharge criteria was not different between the two groups. Emergence delirium occurs frequently with either technique.

Low-threshold lasing at the edge of a photonic stop band in cholesteric liquid crystals.

Low-threshold lasing is observed at the edge of the stop band of a one-dimensional structure-a dye-doped cholesteric liquid-crystal film. The mode closest to the edge has the lowest lasing threshold. The rates of spontaneous and stimulated emission are suppressed within the stop band and enhanced at the band edge. The ratio of right to left circularly polarized spontaneous emission is in good agreement with calculated density of photon states.

Effect of lead on the developing peripheral nervous system.

The effect of lead on the developing nervous system was studied in the Long-Evans rat. Pups were intoxicated with lead from day 2 through the 20th day of life with a dosage of 1 gm Pb/kg body weight. Doses were administered via gastric gavage on the second and third days of life, and bidaily thereafter. Lead-treated and age-matched controls were then studied at selected intervals up to and including 20 days of age. Central and peripheral nervous systems were examined by light and electron microscopy. Morphometric analysis focused on defined segments of proximal and distal sciatic nerves and the 6th dorsal and ventral lumbar roots. For teased fiber studies, a segment of the contralateral proximal sciatic nerve was used. The investigation revealed that during the period studied, the myelin formed is stable. Multiple lead effects, however, were found: the Schwann cell is initially swollen but this effect gradually wanes during the 20 day period; myelin compaction is initially delayed, particularly in the ventral roots; axonal segregation proceeds, but appears to be accelerated in the ventral roots of the lead-treated pups where the larger bundles of naked axons disappear by five days of life. All of the changes noted, except axonal segregation, are reversed in the face of continued lead intoxication. While the hallmarks of "classical" lead neuropathy--segmental demyelination and the selective involvement of large fibers were not observed--the sensitivity of the somatic efferent fibers to lead was apparent in the accentuation of the lead effects in the ventral roots.