Rural and urban differences in physician resource use for low-risk obstetrics

OBJECTIVE: To explore the hypothesis that rural obstetricians (OBs) and family physicians (FPs) utilized fewer resources during the care of the low-risk women who initially booked with them than did their urban counterparts of the same specialties. DATA SOURCES/STUDY DESIGN: A stratified random sample of Washington state rural and urban OBs and FPs was selected during 1989. A participation rate of 89 percent yielded 209 participating physicians. The prenatal and intrapartum medical records of a random sample of the low-risk patients who initiated care with the sampled providers during a one-year period were abstracted in detail and analyzed with the physician as the unit of analysis. Complete data for 1,683 patients were collected. Resource use elements (e.g., urine culture) were combined by standardizing them with average charge data so that aggregate resource use could be analyzed. Intraspecialty comparisons for resource use by category and overall were performed. FINDINGS/CONCLUSIONS: Results show that rural physicians use fewer overall resources in caring for nonreferred low-risk-booking obstetric patients than do their urban colleagues. Resource use unit expenditures showed the hypothesized pattern for both specialties for total, intrapartum, and prenatal care with the exception of FPs for prenatal care. Approximately 80 percent of the resource units used by each physician type were related to hospital care. No differences were shown in patterns of care for most clinically important aspects of care (e.g., cesarean delivery rates), and no evidence suggested that outcomes differed. The overall differences were due to specific components of care (e.g., fewer intrapartum hospital days and less epidural anesthesia).     

Adaptive Multiplication-Free Transversal Equalizers with Application to Digital Radio Systems

Recently, multiplication-free digital filters have been proposed for different applications to digital radio systems and signal processing. The absence of multiplication is obtained by constraining each coefficient to be sum of powers of two. In this way, multipliers are substituted by shift registers and, if appropriate, some adders. The optimal power-of-two coefficients must be computed through a nonlinear optimization procedure. Until now the problem of adapting the power-of-two coefficients of base band transversal equalizers in the case of time-varying channels had not been considered. In this paper two algorithms are proposed to cope with this problem and are compared from the viewpoint of complexity, accuracy, and convergence speed. As an application example, transmission of a biphase PSK digital radio system over a multipath fading channel is considered.     

Advances in Lee–Schetzen Method for Volterra Filter Identification

This paper concerns the identification of nonlinear discrete causal systems that can be approximated with the Wiener–Volterra series. Some advances in the efficient use of Lee–Schetzen (L–S) method are presented, which make practical the estimate of long memory and high order models. Major problems in L–S method occur in the identification of diagonal kernel elements. Two approaches have been considered: approximation of gridded data, with interpolation or smoothing, and improved techniques for diagonal elements estimation. A comparison of diagonal elements estimated, with different methods has been shown with extended tests on fifth order Volterra systems.First Online Version Published in July, 2005     

SPICE-assisted simulation of controlled electric drives: anapplication to switched reluctance drives

An example of simulation of a closed loop controlled electric device that shows the feasibility of simulating the equipment by means of a general-purpose electronic circuit analysis program is described. The SPICE program was used because of its well-known facilities for simulating electronic circuits. A method for extending the SPICE facilities to simulate the electromechanical energy conversion and the drive control is reported. The simulation of a switched reluctance motor drive with closed loop speed control is considered, and the results were validated by experimental tests executed on an industrial drive     

Stress Analysis and Fatigue Life Assessment of a Piston in an Upgraded Engine

Journal of Failure Analysis and Prevention - Need for exploiting a higher performance out of an already designed engine due to the high costs of redesign and manufacturing new engines, makes the...     

Revealing charge-transfer effects in gas-phase water chemistry

An understanding of the interactions involving water and other small hydrogenated molecules such as H(2)S and NH(3) at the molecular level is an important and elusive scientific goal with potential implications for fields ranging from biochemistry to astrochemistry. One longstanding question about water's intermolecular interactions, and notably hydrogen bonding, is the extent and importance of charge transfer (CT) , which can have important implications for the development of reliable model potentials for water chemistry, among other applications. The weakly bound adducts, commonly regarded as pure van der Waals systems, formed by H(2)O, H(2)S, and NH(3) with noble gases or simple molecules such as H(2), provide an interesting case study for these interactions. Their binding energies are approximately 1 or 2 kJ/mol at most, and CT effects in these systems are thought to be negligible. Our laboratory has performed high-resolution molecular-beam scattering experiments that probe the (absolute scale) intermolecular potential of various types of these gas-phase binary complexes with extreme sensitivity. These experiments have yielded surprising and intriguing quantitative results. The key experimental measurable is the "glory" quantum interference shift that shows a systematic, anomalous energy stabilization for the water complexes and clearly points to a significant role for CT effects. To investigate these findings, we have performed very accurate theoretical calculations and devised a simple approach to study the electron displacement that accompanies gas-phase binary intermolecular interactions in extreme detail. These calculations are based on a partial progressive integration of the electron density changes. The results unambiguously show that water's intermolecular interactions are not typical van der Waals complexes. Instead, these interactions possess a definite, strongly stereospecific CT component, even when very weak, where a water molecule may act as electron donor or acceptor depending on its orientation. CT is mediated by an asymmetric role played by the two hydrogen atoms, which causes strong orientation effects. The careful comparison of these calculations with the experimental results shows that the stabilization energy associated to CT is approximately 2-3 eV per electron transferred and may make up for a large portion of the total interaction energy. A simple electron delocalization model helps to validate and explain these findings.     

Tests on self-healing metallized polypropylene capacitors for powerapplications

Results of research carried out at the Institute of Industrial Electrical Engineering of the University of Bologna on self-healing metallized polypropylene (MPP) power capacitors are presented. The aim of the tests is to characterize the degradation of these capacitors when employed in automatic power factor correction systems or in power electronic applications with special reference to the disconnection of the `sprayed ends' from the electrode-edges, one of the main reasons for failure of MPP capacitors employed in the above systems. The research is carried out also in view of the definition of adequate type-test standards, presently not yet available for this kind of application     

A Method to Compute Optimal Gains in Recursive Linear Filtering Applications

Sequence estimation in the presence of additive Gaussian noise and intersymbol interference can be performed by means of discrete Kalman filters. In adaptive receivers for data transmission, the optimal Kalman gains must be computed on-line. A recursive algorithm is presented for this purpose and its performance, i.e., accuracy and computational requirements, is discussed briefly.