Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L.

The authors report the development of an electric oxygen-iodine laser with higher output using a larger product of gain and gain length, g0L. A factor of 4.4 increase in laser power output on the 1315 nm atomic iodine transition was achieved with a factor of 3 increase in gain length. I(2P1/2) is pumped using energy transferred from O2(a1Δ) produced by flowing a gas mixture of O2-He-NO through three coaxial geometry radio-frequency discharges. Continuous wave (CW) average total laser power of 481 W was extracted with g0L=0.042.

Photoluminescence of self-trapped excitons in boron nitride nanotubes.

The excitation energy dependence and temperature dependence of photoluminescence from boron nitride nanotubes and hexagonal BN powder samples are reported. The results are discussed within a model attributing the broad 3.2 eV luminescence from these samples to self-trapped excitons in the low-dimensional structures of BN nanotubes and of nano-arch surface reconstructions on h-BN sheet edge faces in powder. An empirical model accounting for the unusual combination of excitation and temperature dependence of photoluminescence seen in these measurements is suggested. For the model to be consistent with the hypothesis of self-trapped excitons on BN nanotubes, it may be necessary to show that the cores of multiwall nanotubes are selectively probed by light tuned below the h-BN exciton.

A novel polymer nanotube composite for photovoltaic packaging applications.

Packaging of organic photovoltaic (OPV) devices is an important issue which has been rarely addressed in the past. With the recent reports of high efficiency organic photovoltaics (6%), the need to produce materials which can effectively protect the device from degradation due to exposure to oxygen, moisture and radiation is pressing. We report a novel Saran (a co-polymer of vinylidene chloride and acrylonitrile) based polymer nanotube composite, which shows high transparency in the visible region, good barrier properties and thermal stability, for use as an encapsulant for OPV devices. Different loadings of Saran and boron nitride nanotubes were taken and the composites were prepared to optimize the composition of the composite. UV-visible spectroscopy, infra-red spectroscopy and thermal analysis were used to characterize the composite. The barrier properties of the composite were tested on poly(3-hexylthiophene), which is used in high efficiency OPV devices.

Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.

Solid-state NMR characterisation of the thermal transformation of a Hungarian white illite.

(1)H, (27)Al, (29)Si and (39)K solid-state NMR are reported from a Hungarian illite 2:1 clay for samples heated up 1600 degrees C. This single-phase sample has a small amount of aluminium substitution in the silica layer and very low iron-content ( approximately 0.4wt%). Thermal analysis shows several events that can be related to features in the NMR spectra, and hence changes in the atomic scale structure. As dehydroxylation occurs there is increasing AlO(4) and AlO(5)-contents. The silica and gibbsite layers become increasingly separated as the dehydroxylation progresses. Between 900 and 1000 degrees C the silica layer forms a potassium aluminosilicate glass. The gibbsite-layer forms spinel/gamma-Al(2)O(3) and some aluminium-rich mullite. Then on heating to 1600 degrees C changes in the (29)Si and (27)Al MAS NMR spectra are consistent with the aluminosilicate glass increasing its aluminium-content, the amount of mullite increasing probably with its silicon-content also increasing, and some alpha-Al(2)O(3) forming.

Optical properties of vanadium oxide nanotubes.

The optical properties of vanadium oxide nanotube dispersions have been characterized using visible and near infrared absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and nonlinear transmission of optical intensities in the visible and near infrared. Using transmission electron microscopy, optical properties have been correlated to the occurrence of two distinct nanoparticle morphologies: nanotubes and unrolled tubes or platelets. Raman spectroscopy indicates that color changes associated with tub unrolling can be attributed to V2O5 formation. The nanotube and platelet morphologies both show strong optical intensity limiting at 532 and 1064 nm. However, dependencies on repetition rate suggest that slightly different mechanisms dominate at the two wavelengths.

The effects of music on cardiac patients on bed rest.

Hospitalizations that require invasive cardiac procedures or support with an intra-aortic balloon pump can be unsettling. This study was undertaken to measure the effect of a music intervention on physiologic and psychological responses of patients on bed rest due to procedural sheaths or an intra-aortic balloon pump. A randomized, two-group, pretest/post-test design was utilized to measure the effect of a 30-minute music intervention on heart rate, blood pressure, respiratory rate, skin temperature, pain perception, and mood states. One hundred forty subjects participated, 65 in the control group and 75 in the treatment group. There were no significant differences between the groups in demographic, clinical, or baseline variables, except for respiratory rate. After the music intervention, there were reductions in blood pressure, respiratory rate, and psychological distress, as measured by the Profile of Mood States (p < 0.05). Music appeared to affect selected physiologic responses and reduce psychological distress in patients on bed rest.

Activities of the APN to enhance unpartnered elders self-efficacy after myocardial infarction.

Unpartnered elders recovering from a myocardial infarction find themselves with limited support to contend with their physical and emotional recovery. The advanced practice nurse (APN) can play an instrumental role in improving the health outcomes of these elders. Detailed description of the activities of the APN that affect patient outcomes in current randomized clinical trials have been inadequate in published reports. Therefore, the purpose of this article is to describe the activities of an APN in a nurse-coached intervention study for unpartnered elders post-myocardial infarction. Thematic analysis from the subject logs and narratives from the APN identified the four themes of patient education, validation/feedback, encouragement/support, and problem solving as the unique activities of the APN. These activities enhanced the recovery of these vulnerable unpartnered elders after a myocardial infarction.

A knowledge-based patient assessment system: conceptual and technical design.

This paper describes the design of an inpatient patient assessment application that captures nursing assessment data using a wireless laptop computer. The primary aim of this system is to capture structured information for facilitating decision support and quality monitoring. The system also aims to improve efficiency of recording patient assessments, reduce costs, and improve discharge planning and early identification of patient learning needs. Object-oriented methods were used to elicit functional requirements and to model the proposed system. A tools-based development approach is being used to facilitate rapid development and easy modification of assessment items and rules for decision support. Criteria for evaluation include perceived utility by clinician users, validity of decision support rules, time spent recording assessments, and perceived utility of aggregate reports for quality monitoring.

The peer advisor experience providing social support.

Research shows a link between increased social support and decreased complications after myocardial infarction (MI). In a current randomized controlled trial (RCT), a social support intervention administered by nurse and peer advisors is being examined to determine its influence on the health outcomes of unpartnered, post-MI elders. This qualitative study (as part of the larger RCT) sought a better understanding regarding the experience of the peer advisor. Data sources included peer advisor logs, a focus group, and telephone interviews with peer advisors. Findings revealed that helping, mutual sharing, committing, and benefiting are characteristics of peer experiences. Primarily because of their personal experience of recovery from MI, peer advisors had a remarkable ability to relate to assigned post-MI elders, offering a unique form of social support complementary to current health practices.

Changes in health status and quality of life and the impact of uncertainty in patients who survive life-threatening arrhythmias.

OBJECTIVE: The purpose of this study was to describe the changes in perception of health status and quality of life from before treatment to 6 months after and the impact of uncertainty on these variables in survivors of life-threatening arrhythmia. DESIGN AND SETTING: A descriptive correlational design at a large urban teaching hospital. MEASURES: We measured health status, quality of life, and uncertainty before treatment and 6 months after a life-threatening arrhythmia. RESULTS: Survivors included 66 men and 15 women, 41 of whom received pharmacologic therapy and 36 of whom received an implantable cardioverter defibrillator (ICD), completed the Medical Outcomes Survey (SF-36), Ferrans and Powers Quality of Life Index (QLI), and the Mishel Uncertainty in Illness Scale (MUIS-C) before treatment and 6 months after. There were significant improvements in the mental and physical health composite summaries as measured by the SF36 (P <.01). Conversely, there were significant reductions in the overall score and specifically in socioeconomic and psychological/spiritual quality of life domains as measured by the QLI (P <.05). An increased perception of uncertainty was related to decreased perception of health status and quality of life at both measurement times, with higher correlations 6 months later. CONCLUSIONS: Survivors demonstrated improvements in perceived health status, although this did not appear to translate into improvements in the subjective domains of quality of life. The overall quality of life and the domains of psychological/spiritual state and socioeconomic status were lower 6 months after a life-threatening arrhythmia. Uncertainty had a significant impact on these perceptions, identifying an area for nursing interventions.

A new genetic algorithm technique in optimization of permanent 125I prostate implants.

Real time optimized treatment planning at the time of the implant is desirable for ultrasound-guided transperineal 125I permanent prostate implants. Currently available optimization algorithms are too slow to be used in the operating room. The goal of this work is to develop a robust optimization algorithm, which is suitable for such application. Three different genetic algorithms (sGA, sureGA and securGA) were developed and compared in terms of the number of function evaluations and the corresponding fitness. The optimized dose distribution was achieved by searching the best seed distribution through the minimization of a cost function. The cost function included constraints on the periphery dose of the planned target volume, the dose uniformity within the target volume, and the dose to the critical structure. Adjustment between the peripheral dose, the dose uniformity and critical structure dose can be achieved by varying the weighting factors in the cost function. All plans were evaluated in terms of the dose nonuniformity ratio, the conformation number and the dose volume histograms. Among these three GA algorithms, the securGA provided the best performance. Within 2500 function evaluations, the near optimum results were obtained. For a large target volume (5 cm x 4 cm x 4.5 cm) including urethra with 20 needles, the computer time needed for the optimization was less than 5 min on a HP735 workstation. The results showed that once the best set of parameters was found, they were applicable for all sizes of prostate volume. For a fixed needle geometry, the optimized plan showed much better dose distribution than that of nonoptimized plan. If the critical structure was considered in the optimization, the dose to the critical structure could be minimized. In the cases of irregular and skewed needle geometry, the optimized treatment plans were almost as good as ideal needle geometry. It is concluded that this new genetic algorithm (securGA) allows for an efficient and rapid optimization of dose distribution, which is suitable for real time treatment planning optimization for ultrasound-guided prostate implant.

Barriers and facilitators to the utilization of nursing research.

The nurse in clinical practice must demonstrate a scientific base for practice grounded in research findings. The purpose of this study was to explore the nurse's perception of the barriers and facilitators to using research findings in nursing practice. A survey methodology was used, and a sample of 356 practicing registered nurses responded. Data were collected using a scale that rated the barriers and facilitators to research utilization. The greatest barriers were insufficient time on the job to implement new ideas, lack of knowledge of nursing research findings, and inaccessibility of relevant literature. The advanced practice nurse is in a pivotal position to decrease the barriers to research utilization.

The importance of self-efficacy expectations in elderly patients recovering from coronary artery bypass surgery.

OBJECTIVE: To describe and test a model of recovery in the elderly after coronary artery bypass surgery derived from Self-Care and Self-Efficacy Theory. DESIGN: Prospective, longitudinal, repeated measures. SETTING: Two large urban teaching hospitals on the East Coast. PATIENTS: One hundred thirty-three adults over the age of 65 years who had coronary artery bypass surgery on hospital admission. There were 32 women and 101 men with an age range of 65 to 87 years (M = 71.8 years +/- 4.8 years) in whom 77.5% were in a New York Heart Association class of 3 or 4, indicating significant functional limitations. OUTCOME MEASURES: Self-care agency, self-efficacy expectations, and the performance of self-care/recovery behaviors at discharge, 6, and 12 weeks after coronary artery bypass surgery. INSTRUMENTS: The exercise of self-care agency was measured with the Exercise of Self-Care Agency Scale, self-efficacy expectation, and the performance of self-care/recovery behavior by the Jenkins Self-Efficacy Expectation Scales and Activity Checklists. Data were collected at discharge, 6 weeks, and 12 weeks after surgery for the specific behaviors of walking, climbing stairs, resuming general activities, and the performance of roles. RESULTS: Repeated measures analysis of variance revealed significant changes in self-care agency, the self-efficacy expectations for all behaviors, and the performance of the behaviors for walking, resuming general activities, and performance of roles over the recovery period (p < 0.01). CONCLUSIONS: In support of the model, self-efficacy expectations mediated between self-care agency and all self-care/recovery behaviors at selected times. Comparison of the performance of self-care/recovery behaviors with other samples from the literature found recovery in the elderly to be protracted. Nurses can be pivotal in providing the elderly with accurate projections of recovery and an environment to support the initial mastery of self-care/recovery behaviors to promote optimal health in this vulnerable population.

Effects of a nonhomogeneous gain saturation law on predicted performance of a high-gain and a low-gain laser systems.

A modified Rigrod theory that uses a nonhomogeneous gain saturation law is used to model outcoupled, total, and intracavity power from a high-gain and a low-gain cw HF chemical laser with good accuracy. The homogeneous gain saturation law is found to have significant limitations when used to model total power data over a wide range of threshold gain values. The use of a nonhomogeneous gain saturation law indicates that a gain saturation law parameter of m = 1.2 models University of Illinois at Urbana-Champaign supersonic cw HF fundamental laser data more accurately than a homogeneous gain saturation law (m = 1). A completely inhomogeneous saturation law (m = 2) models University of Illinois at Urbana-Champaign supersonic HF overtone laser data more accurately than a completely homogeneous gain saturation law.

Maximizing output power of a low-gain laser system.

Rigrod theory was used to model outcoupled power from a low-gain laser with good accuracy. For a low-gain overtone cw HF chemical laser, Rigrod theory shows that a higher medium saturation yields a higher overall overtone efficiency, but does not necessarily yield a higher measurable power (power in the bucket). For low-absorption-scattering loss overtone mirrors and a 5% penalty in outcoupled power, the intracavity flux and hence the mirror loading may be reduced by more than a factor of 2 when the gain length is long enough to saturate the medium well. For the University of Illinois at Urbana-Champaign overtone laser that has an extensive database with well-characterized mirrors for which the Rigrod parameters g(0) and I(sat) were firmly established, the accuracy to which the reflectivities of high-reflectivity overtone mirrors can be deduced by using measured mirror transmissivities, measured outcoupled power, and Rigrod theory is approximatly ±0.07%. This method of accurately deducing mirror reflectivities may be applicable to other low-gain laser systems that use high-reflectivity mirrors at different wavelengths. The maximum overtone efficiency is estimated to be approximately 80%-100%.

Late results with Carpentier-Edwards porcine bioprosthesis.

From 1977 to 1984, 429 patients underwent aortic valve replacement (AVR), and 339 underwent mitral valve replacement (MVR) with a Carpentier-Edwards bioprosthesis. Early mortality for AVR was 4.6% (isolated AVR, 1.9%) and for MVR was 5.3% (isolated MVR, 4.1%). Follow-up was 99.3% complete at a mean of 5.9 years. Actuarial event-free rates at 10 years for AVR and MVR were, respectively, 1) for structural valve deterioration, 91.4 +/- 3.2% versus 75.1 +/- 4.0% (p less than 0.01); 2) for nonstructural dysfunction, 100% versus 97.8 +/- 1.6% (p = NS); 3) for thromboembolism, 90.6 +/- 2.3% versus 87.3 +/- 2.6% (p = NS); 4) for anticoagulant-related bleeding, 95.3 +/- 1.1% versus 88.6 +/- 2.4% (p = 0.05); 5) for endocarditis, 87.8 +/- 5.7% versus 90.6 +/- 2.4% (p = NS); 6) for reoperation, 91.0 +/- 2.5% versus 74.4 +/- 3.7% (p less than 0.01); 7) for valve-related mortality, 76.1 +/- 6.9% versus 71.4 +/- 5.2% (p = 0.01); 8) for permanent physical impairment, 85.0 +/- 3.0% versus 71.5 +/- 3.6% (p less than 0.01); and 9) for combined operative mortality, valve-related mortality, and reoperation, 68.7 +/- 6.4% versus 51.5 +/- 4.9% (p = 0.01). No structural valve dysfunction was observed in any AVR patient whose valve was inserted after age 70. Age at operation was the only factor that predicted structural valve deterioration (p less than 0.01).

Comparison of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty as initial treatment strategies.

Early and late results of primary nonemergency coronary artery bypass grafting in 1,000 consecutive patients and primary nonemergency percutaneous transluminal coronary angioplasty performed concurrently in 389 patients were retrospectively compared. The coronary bypass population was significantly older and more symptomatic and had more prior myocardial infarctions, more left main and multiple-vessel coronary artery disease, and poorer ventricular function. Hospital mortality rates for coronary bypass grafting and angioplasty were 0.4% and 0.5%, respectively, and infarction rates were 1.7% and 5.1%, respectively (p less than 0.01). Including hospital events for the coronary bypass and angioplasty populations, actuarial survival at 5 years was 92.3% versus 96.3% (p = 0.04), freedom from myocardial infarction was 94.6% versus 88.1% (p less than 0.001), freedom from subsequent angioplasty was 99.5% versus 75.2% (p less than 0.001), freedom from subsequent coronary bypass grafting was 98.8% versus 84.9% (p less than 0.001), and freedom from all morbidity and mortality was 87.1% versus 66.0% (p less than 0.001), respectively. By Cox regression analysis for all 1,389 patients, only diminished ejection fraction and advanced age predicted poor long-term survival (p less than 0.001). The only significant predictor of nonfatal late events was having had coronary angioplasty.

Event-free survival following nonemergency myocardial revascularization during hypothermic fibrillatory arrest.

To better assess the late results of hypothermic fibrillatory arrest during myocardial revascularization, 1,000 consecutive patients having nonemergency coronary artery grafting during hypothermic fibrillatory arrest from August, 1979, through November, 1984, were studied to determine event-free survival. Hospital mortality was 0.4% and the rate of perioperative myocardial infarction, 1.8%. At follow-up (mean, 30.5 months), 11 patients had sustained an interval nonfatal myocardial infarction, 3 had had percutaneous angioplasty, and 2 had undergone reoperative revascularization. Actuarial survival at five years was 91.6 +/- 2.0%. Actuarial event-free rates at five years were 97.7 +/- 0.8% for myocardial infarction, 99.4 +/- 0.4% for percutaneous transluminal coronary angioplasty, 99.5 +/- 0.4% for reoperative revascularization, and 88.6 +/- 2.2% for all combined morbidity and mortality. Among the 122 patients meeting randomizable admission criteria of the Coronary Artery Surgery Study, there were no operative deaths and no perioperative infarctions, and the actuarial survival was 97.5% at five years. Hypothermic fibrillatory arrest is effective for myocardial preservation during coronary revascularization and when combined with complete revascularization, yields excellent event-free survival.