Microscale Inhomogeneities in Aluminum Solution-Doping of Silica-Based Optical Fibers

The microstructure of aluminum (Al) solution-doped soot layers in modified chemical vapor deposition fabrication of silica-based optical fibers has been studied. It is shown that such Al doping is predominantly determined by deposition temperature. Radial and longitudinal Al doping distributions have been investigated in soot layers, in fully sintered glass layers, and in collapsed preforms. Formation mechanisms are discussed.     

Multiple roles, social networks, and women's well-being.

In contrast to earlier approaches to the study of multiple roles, our research was concerned with the frequency and conditions under which both positive and negative outcomes occur. Using data from a random sample of 235 married female nurses, we focused on marital and job satisfaction as important criteria of success in managing multiple roles. In the first phase of the research, a cluster analysis identified five different profiles of marital and job satisfaction. Of the two most positive profiles, one was defined by high scores in both areas, the other by high job satisfaction but only moderate marital satisfaction. In two other profiles, women were very dissatisfied with one role and at best moderately satisfied with the other. In the second phase, the profiles were found to be meaningfully associated with measures of psychological symptomatology and overall life satisfaction. The third phase considered how the profiles were linked to measures of social support and social rejection provided by five key network members. The strongest univariate profile discriminator was the level of work rejection from the spouse. A discriminate function analysis revealed that the level of spouse's work rejection was even more powerful when it was compared to the level of work rejection received from the next closest family member (typically the mother). (53 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prognostic classification for esophageal atresia and tracheoesophageal fistula: Waterston versus Montreal

Since 1962, the Waterston classification has been used to stratify neonates who have esophageal atresia (EA) and/or tracheoesophageal fistula (TEF) into prognostic categories based on birth weight, the presence of pneumonia, and the identification of other congenital anomalies. In response to advances in neonatal care, the surgeons from the Montreal Children's Hospital proposed a new categorization system in 1993 in an attempt to define the current risk factors for patients who have EA/TEF. In the Montreal experience only two characteristics independently affected survival: preoperative ventilator dependence and associated major anomalies. The goal of this study was to determine which system had the greatest validity for the evaluation of prognosis in our patients with EA/TEF. The charts of 94 patients who had EA/TEF treated between 1972 and 1991 were reviewed. Patients were classified using both the Waterston and Montreal systems. Groups were compared with Fisher's Exact test using a 95% confidence level for statistical significance. Eleven infants were ventilator dependent preoperatively; 62 children had major associated anomalies, 8 of which were considered life threatening. Sixteen children died within 4 years, eight during their initial hospital stay. Five of the eight early postoperative deaths occurred in the highest-risk patients (Waterston C or Montreal II). Analysis was performed for multiple risk factors and mortality. As in the Montreal study, the presence of life-threatening and major congenital anomalies represented significant risk factors for death. Pulmonary disease as delineated by ventilator dependence appeared to be more accurate than pneumonia. This study confirms the accuracy of the Montreal classification in defining prognosis for EA/TEF. The Montreal system more accurately identifies children at highest risk than the Waterston classification.     

The catalytic nanodiode. Its role in catalytic reaction mechanisms in a historical perspective

Catalytic nanodiodes, Pt/TiO₂ or Pt/GaN produce continuous flow of hot electron current during carbon monoxide oxidation for hours in the 80–150 °C temperature range at pressures of 100 Torr of O₂ and 40 Torr of CO. These observations provide proof of the Schottky diode model of oxide supported metal catalysis of many reactions that have been proposed by Schwab, Solymosi and others since the 1960s. The flow of hot electrons should influence chemistry at oxide–metal interfaces and the metal particle size dependence of catalytic activity and selectivity.     

Progression of interproximal caries in the primary dentition

In the patients with invasion to the aortic window, we performed operation via median sternotomy combined with anteroaxillar thoracotomy. In such patients with T4 invasion, conventional pneumonectomy could not be performed because of the extensive invasion near the main pulmonary artery trunk. In these patients in this study, complete resection of the involved pulmonary artery could be performed using a vascular clamp without CP bypass. Operative technique was as follows: first, the pericardium was opened and taping of the aorta was applied. When the uninvolved part of the intrapericardial pulmonary artery was long enough to cut, we could use a stapling device, but the stapling device could not be used in many cases because the length of the uninvolved segment was too short to cut the left pulmonary artery. In order to carry out complete resection, it was necessary to clamp the central part of the main pulmonary artery diagonally from the left lower side to the right upper side. The pulmonary arterial stump was closed with continuous 4-0 monofilament mattress and over and over suture. We recommend an aggressive surgical approach for the tumor with invasion to the aortic window, because the prognosis is dismal in nonresected locally advanced lung cancer.     

The along track scanning radiometer for ERS-1-scan geometry anddata simulation

The first European remote-sensing satellite (ERS-1) will carry the along track scanning radiometer (ATSR). which has been specifically designed to give accurate satellite measurements of sea surface temperature (SST). Details of the novel scanning technique used by the ATSR are given, and data from the NOAA-9 AVHRR instrument are used to simulate raw ATSR imagery. Because of the high precision of the onboard blackbodies, the active cooling of the detectors, 12-b digitization, and dual-angle capability, the ATSR promises to achieve higher-accuracy satellite-derived SSTs than are currently available     

Tunable sampled-grating DBR lasers using quantum-well intermixing

Widely tunable lasers are key components for wavelength division multiplexing fiber optic networks. They reduce cost in sparing, enable dynamic networking applications, and present opportunities for future monolithically integrated wavelength division multiplexing components. The sampled-grating distributed Bragg reflector (SGDBR) laser is ideal for these purposes. The authors present a centered quantum-well SGDBR laser which uses quantum-well intermixing in order to improve device characteristics over previous designs. The mode overlap is improved by 50% over the offset quantum-well design, improving the modal gain. Current injection tuning in the intermixed material is demonstrated for the first time; the maximum modal group index change was measured to be 1%.     

Effective parameter estimation within a multi-dimensional population balance model framework

This study considers optimization problems with multi-dimensional population balance models embedded. The objective function is formulated as a least-squares problem, minimizing the difference between target data and simulated model output and the goal is to find model parameter values that best fit the data. Results show that derivative-free methods, such as the Nelder–Mead simplex method, fail to converge to an optimal solution. A similar result was obtained with gradient-based methods such as BFGS, quasi-Newton, Newton, Gauss–Newton, Levenberg–Marquardt and SQP, and with a stochastic genetic algorithm. It was hypothesized that three main issues could contribute to these convergence failures: (1) gradients were calculated based on finite differences, and as a result of improper step size determination, the numerical error could be prohibitive resulting in inaccurate derivative information, (2) the parameters may not be identifiable and (3) numerical instability could occur during the course of optimization. To circumvent these issues, this work addresses the calculation of derivative information based on automatic differentiation and sensitivity analysis to ensure increased accuracy. Issues such as parameter identifiability are also dealt with by analyzing an accurate Fisher information matrix. Given the computational burden in calculating accurate Jacobians and Hessians, compounded by the potential nonsmoothness introduced into the objective function as a result of granule nucleation, other optimization strategies may be warranted and this work addresses those accordingly. Overall, by systematically assessing the problem formulation and mechanisms, the results show that substantial improvements in convergence can be achieved by utilizing appropriate optimization techniques, thus leading to more successful and optimal parameter estimation.