Showing papers by "James Taylor published in 1997"

Visual Acuity, Erythrocyte Fatty Acid Composition, and Growth in Term Infants Fed Formulas with Long Chain Polyunsaturated Fatty Acids for One Year

Abstract: The CNS and the retina are enriched in long chain polyunsaturated (LCP) fatty acids, specifically docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6), which are present in human milk but not in most infant formulas. In the present study of 134 formula-fed and 63 breast-fed infants, we prospectively evaluated whether providing a source of DHA and AA or DHA alone in formula would increase red blood cell (RBC) phospholipid levels of these fatty acids, enhance visual function, or affect growth during the first year. Healthy term infants < 7 d old were randomized to be fed formulas containing linoleic acid (approximately 10% kcal) and alpha-linolenic acid (approximately 1% kcal) plus (1) no added LCP fatty acids (control formula), (2) DHA (0.12 wt% fatty acids) and AA (0.43 wt%) from egg yolk phospholipid (AA + DHA formula), or (3) DHA (0.2 wt%) from fish oil (DHA formula). A breast-fed group was studied concurrently and permitted formula supplementation after 3 mo. Visual acuity was measured using both the acuity card procedure and a visual evoked potential method at 2, 4, 6, 9, and 12 mo. Infants fed the control formula had 10-40% lower RBC levels of DHA and AA than infants in the breast-fed group. Infants fed the AA + DHA formula had levels of both LCP within approximately 10% of the values for infants in the breast-fed group, and infants fed the DHA formula had 25-55% higher DHA levels and 15-40% lower AA levels. There were no differences in growth or in visual function during this 12-mo feeding study.

Supercontinuum self-Q-switched ytterbium fiber laser

Abstract: We have discovered a new mechanism for passive Q switching of fiber lasers. 10-kW peak power pulses with ∼2-ns pulse widths are reported from a diode-pumped ytterbium-doped fiber laser. The laser generates a high-brightness Raman-dominated supercontinuum spectrum covering the complete window of transparency of silica fiber in the infrared from 1.06 to 2.3 µm

The Influence of Provider Behavior, Parental Characteristics, and a Public Policy Initiative on the Immunization Status of Children Followed by Private Pediatricians: A Study From Pediatric Research in Office Settings

Abstract: Objectives. To determine the relative impact of parental characteristics, provider behavior, and the provision of free vaccines through state-sponsored vaccine volume programs (VVPs) on the immunization status of children followed by private pediatricians. Study Design. Retrospective and cross-sectional surveys of immunization data. Setting. The offices of 15 private pediatricians, from 11 states, who were members of the Pediatric Research in Office Settings network. Seven of these physicians used vaccines provided through VVPs. Patients. Children 2 to 3 years old followed by the participating physicians. Methods. The immunization status of children was assessed from two separate samples. For sample 1, immunization data were abstracted from the medical records of 60 consecutive eligible children seen in each office. Parents of the selected children indicated the method of payment for immunizations and the education levels of the mothers. Because this cross-sectional survey might have oversampled frequent health care users, a retrospective chart review of up to 75 randomly selected children in each pediatrician9s practice was also conducted (sample 2). Additional data were collected from the parents of children in sample 2 by telephone interviews. For both samples, patients were considered to be fully immunized if they had received four diphtheria-tetanus-pertussis/diphtheria-tetanus vaccines, three oral poliovirus/inactivated poliovirus vaccines, and one measles-mumps-rubella vaccine before their second birthdays. Before collecting vaccination data, pediatricians completed a survey detailing their immunization beliefs and practices. Logistic regression was used to identify factors that were independently associated with a child being fully immunized. Results. For sample 1, 81.7% of the 857 children surveyed were fully immunized. Practitioner-specific immunization rates varied widely, ranging from 51% to 97%. The immunization rate of children who received vaccines provided by VVPs was similar to that of children whose immunizations were not provided by VVPs (81.2% vs 82.2%; odds ratio [OR] for a VVP as a predictor for being fully immunized, 0.94, 95% confidence interval [CI], 0.66 to 1.32). In addition, parents who paid for immunizations out of pocket were as likely to have fully immunized children as those who had little or no out-of-pocket expenditures for vaccines (OR, 1.13; 95% CI, 0.75 to 1.13). In the logistic model, only individual pediatrician and size of the metropolitan area in which the pediatrician9s practice was located were significant predictors of a child9s immunization status. The results from sample 2 were similar; 82.1% of the 772 surveyed patients were fully immunized. With sample 2, individual pediatrician and age of the child at the time of the survey were the only predictors of immunization status. The OR of a VVP as a predictor of a child being fully immunized was 1.37 (95% CI, 0.65 to 2.90). Conclusions. Individual provider behavior may be the most important determinant of the immunization status of children followed by private pediatricians. In our samples, the effect of parental characteristics was limited. State-sponsored VVPs were not associated with higher immunization rates, perhaps because cost of vaccines did not seem to be a significant barrier to immunization in this population.

A Randomized Controlled Trial of Group Versus Individual Well Child Care for High-risk Children: Maternal-Child Interaction and Developmental Outcomes

Abstract: Objective. To determine if group well child care (GWCC) for high-risk children affects maternal-child interaction and development as compared to these outcomes in children receiving traditional individual well child care (IWCC). Study Design. Randomized controlled trial. Participants. Infants less than 4 months old at the initiation of the study who came from high-risk families. Families were classified as high risk, and eligible for study participation, if the mother had one or more of the following characteristics: poverty, single marital status, less than a high school education, age less than 20 years at delivery, previous substance abuse, or a history of abuse as a child. Setting. Two urban, university pediatric clinics in Seattle, Washington. Interventions. Study children were randomized to receive GWCC or IWCC prior to the first study visit at the age of 4 months. Study health supervision visits were scheduled at 4, 5, 6, 8, 10, 12, and 15 months of age. For children randomized to receive GWCC, study visits consisted of an age-matched group discussion of child rearing issues, either preceding or following a brief physical examination. After the 15-month visit, development of study patients was assessed by the use of Bayley Scales of Infant Development (Bayley). Maternal-child interaction and the home environment were evaluated by the use of the Nursing Child Assessment Teaching Scale (NCATS) and the Home Observation for Measurement of the Environment (HOME), respectively. Results. At least one outcome measure was obtained on 114 children; 86 patients completed all three outcome measures. Bayley psychomotor mean scores were 103.6 ± 11.5 for GWCC patients versus 100.0 ± 12.4 for those receiving IWCC ( P = .14); mean scores for the mental section were 99.3 ± 14.8 and 100.4 ± 14.3, respectively ( P = .71). The prevalence of high-risk maternal-child interactions was 10% in both the GWCC and IWCC groups. A high-risk home environment was found in 16% of IWCC patients versus 4% of those randomized to GWCC (odds ratio comparing IWCC to GWCC 4.6, 95% confidence interval 0.78, 26.0, after controlling for confounding variables). Provider time was similar among groups (mean number of minutes/patient/study visit: 19.8 ± 5.6 and 20.4 ± 6.7 for GWCC and IWCC, respectively, P = .66). Conclusion. GWCC is a viable alternative to IWCC for high-risk children. Developmental outcomes and maternal-child interaction are at least as good for children who received GWCC as compared to traditional IWCC, without any increase in provider time required. well child care, child development, maternal-child interaction, Bayley Scales of Infant Development, Nursing Child Assessment Teaching Scale, Home Observation for Measurement of the Environment.

Device for closure of puncture wound

Abstract: A surgical stapler for use at visually inaccessible sites comprises a shaft having a stapler head at its distal end and a guide means for accommodating a separate, pre-positioned guide wire whereby the stapler may be slid bodily along the guide wire to guide the stapler head towards the exterior of a blood vessel. A blood vessel locator tube has a forward end projecting forwardly of the stapler head for entering the blood vessel through a puncture site and a rear end remote from the distal end of the shaft. The locator tube allows the positioning of the stapler head at the blood vessel to be indicated by a flow of blood from the rear end of the tube.

Device for closure of a puncture wound

Abstract: A surgical stapling device is described which comprises a shaft (6) with a hollow channel running throughout its length which terminates at its distal end in front of a surgical staple which is housed in the distal end of the stapling device. Closure of a puncture can be achieved after the stapler has been brought into position over a guidewire (1) which has previously been placed into the blood vessel (5) via a percutaneous approach (15, 4). The exact site of the stapling device in relation to the puncture site may be confirmed by advancing a blood vessel puncture site locator tube (2) over the guidewire running through the shaft of the stapler and into the blood vessel puncture site (14). Backflow of blood will be observed. Following either withdrawal of the locator tubing or leaving it in place over the guidewire, the staple is deployed into the walls of the artery (9), and after approximating its opposite walls, is automatically ejected from the stapler. The stapler is then removed from the percutaneous tract over the guidewire which itself is removed when haemostasis is observed.

1083 nm ytterbium doped fibre amplifier for optical pumping of helium

Abstract: A combination of a narrow linewidth, tunable DBR diode laser and high power ytterbium fibre amplifier in a master oscillator power fibre amplifier (MOPFA) configuration is demonstrated for efficient optical pumping of helium. A compact and efficient diode pumped prototype system is shown to compare favourably with alternative laser sources for production of hyperpolarised /sup 3/He using direct pumping for medical application in MRI.

Health Care Utilization and Health Status in High-risk Children Randomized to Receive Group or Individual Well Child Care

Abstract: Objective . To determine if health care utilization and health status among high-risk children is modified by the use of group well child care (GWCC) as compared with traditional one-to-one individual well child care (IWCC). Study Design . Randomized controlled trial. Participants . Children less than 4 months old from families with at least one of the following maternal risk factors: poverty, single marital status, age Setting . Two urban, university pediatric clinics in Seattle, Washington. Interventions . Children were randomized to receive GWCC or IWCC at the time of enrollment. Health supervision visits with two study nurse practitioners were scheduled at 4, 5, 6, 8, 10, 12, and 15 months of age. GWCC study visits consisted of a group discussion of age-appropriate child-rearing issues, along with a physical examination, health screening, and immunizations. Health care utilization among children receiving GWCC and those randomized to IWCC was assessed using the following measures: compliance with study visits, compliance with any age-appropriate health supervision visit, emergency department utilization, and immunization rates (defined as the proportion of children in each group who had received all recommended vaccines by 1 year of age). Provider time for GWCC and IWCC study visits was also recorded. Health status was measured using Stein9s Functional Status IIR, completed by the mothers of study patients when their children completed the study at 15 months of age. Results . A total of 106 children received GWCC, whereas 104 were randomized to IWCC. Compliance with scheduled study visits was 47% for GWCC patients and 54% for IWCC recipients; overall compliance with any age-appropriate health supervision visit was 68% and 66%, respectively. Provider time was similar for GWCC and IWCC visits. By the age of 1 year, 67% of GWCC recipients and 73% of those receiving IWCC had received three DTP/DT, three OPV/IPV, three Hib, and three hepatitis B immunizations. A total of 242 emergency department visits were made by study patients during their enrollment in the project; there was no difference in the average number of visits between GWCC or IWCC children. However, children receiving IWCC were more likely to have at least one emergency department visit than GWCC recipients. At the conclusion of the project, health status, as measured by the Functional Status IIR, was similar in GWCC and IWCC patients (mean scores 92.4 ± 1.4 and 92.5 ± 1.1, respectively). Conclusions . Health care utilization and health status was similar in high-risk children whether they received GWCC or IWCC. GWCC is a viable format for health supervision visits in this population.

Dysregulation of Mesoprefrontal Dopamine Neurons Induced by Acute and Repeated Phencyclidine Administration in the Nonhuman Primate: Implications for Schizophrenia

Abstract: Publisher Summary Phencyclidine (PCP) induces several distinct behavioral effects in humans and animals that appear to represent schizophrenia-like symptomatology. In humans, acute PCP exposure can induce both positive and negative symptoms of schizophrenia. In contrast, repeated exposure to PCP in humans can lead to enduring presentation of both negative and positive symptoms of schizophrenia. Thus, repeated PCP administration may induce neurobiological defects that mimic those present in the brain of patients with schizophrenia. This chapter discusses some of the recent studies on the effects of acute and repeated PCP administration on the rodent and nonhuman primate dopamine (DA) systems and how these neurobiological effects may underlie the psychotomimetic properties of PCP. The chapter also evaluates the relevance of DAergic dysfunction for the hypoglutamatergic and neuropathological hypotheses of PCP's effects. In the primate, acute PCP administration causes a selective activation of DA metabolism in the frontal cortex, while sparing subcortical DA systems. It is suggested that activation of DA systems by PCP may be involved in the development of neuropathology after acute PCP administration. Taken together, these studies indicate that repeated PCP administration may model the cognitive dysfunction of schizophrenia and suggest that this dysfunction may be because of an inhibition of DAergic function in the PFC. Further, this paradigm may represent a step forward in biological psychiatric research by offering a tool for evaluating the pathophysiology of the deficits of schizophrenia and a mechanism for the evaluation of novel agents that may be able to ameliorate the typically treatment-refractory negative symptoms in this debilitating disorders.

10 GHz 1.9 ps actively modelocked fibre integrated ring laser at 1.3 [micro sign]m

Abstract: The authors report a novel 1.3 /spl mu/m actively modelocked semiconductor ring laser which generates near transform-limited pulses as short as 1.9 ps at a repetition rate of 10 GHz. The laser is constructed from discrete fibre pigtailed components and an electroabsorption modulator is used as the modelocking element.

All-solid-state diode-pumped Cr:LiSAF femtosecond oscillator and regenerative amplifier

Abstract: :LiSrAlF6 (Cr:LiSAF) regenerative amplifier, seeded by a diode-pumped Cr:LiSAF femtosecond oscillator. The amplifier produced pulses of less than 200 fs duration and greater than 1 μJ energy at repetition rates of up to 25 kHz.

A duration-tunable, multiwavelength pulse source for OTDM and WDM communications systems

Abstract: We describe a highly flexible ultrashort optical pulse source capable of generating duration-tunable pulses at single or multiple wavelengths. The technique we report is based on the filtering of the broad spectrum of femtosecond solitons which are generated using an electroabsorption modulator combined with nonlinear compression. The simplicity and robust nature of this source make it highly stable and we demonstrate the generation of pulses at a repetition rate of 10 GHz with durations in the femtosecond and picosecond regimes and the simultaneous generation of eight 10-GHz channels of picosecond pulses with a channel spacing of 3.5 nm.

MINLP formulation of optimal reactive power flow

Abstract: A method for the solution of optimal reactive power dispatch which treats var sources and transformer tap ratios as discrete variables is presented. The optimal reactive power flow problem is inherently a mixed-integer nonlinear programming (MINLP) problem. For finding the global optimal solution of this problem, an MINLP formulation is proposed and executed. In this formulation, discrete variables, var sources and tap ratios, are modeled as binary variables. The MINLP problem with only continuous and binary variables is solved by an outer-approximation/equality-relaxation algorithm. In this algorithm, the MINLP problem is decomposed into a mixed-integer linear programming master problem, and an nonlinear programming (NLP) subproblem. These two subproblems are solved successively until convergence criteria are met. A sample network is used for testing the proposed method. The results verify that the MINLP approach can find the global optimum, while NLP algorithms give a suboptimal solution.

Rigorous hybrid systems simulation of an electro-mechanical pointing system with discrete-time control

Abstract: Earlier research in the modeling and simulation of hybrid systems led to the development of a general hybrid systems modeling language (HSML). Effort is underway to implement this concept in software. The standard MATLAB model framework and integration algorithms have been extended to support state-event handling in continuous-time components and to handle embedded discrete-time components. In this paper we overview the algorithmic implementation of the HSML language constructs for dealing with state events and embedded discrete-time modules in MATLAB. An extensive example of an electro-mechanical pointing system with stiction under discrete-time control is presented to demonstrate the efficacy of these extensions.

Increasing plasma etch resistance of resists using fullerene additives

Abstract: We utilize a new class of additive, Fullerenes, which appear to impart superior plasma etch resistance to resist films compared to other additives reported in the literature. [R. R. Kunz, S. C. Palmateer, A. R. Forte, R. D. Allen, G. M. Wallraff, R. A. DiPietro, and D. C. Hofer, Proc. SPIE 2724, 365 (1996).] The plasma etch resistance of PMMA impregnated with [60]Fullerenes was compared directly to pure PMMA; adamantane- and 1-chloroadamantane-impregnated PMMA; the novolac-based, e-beam/x-ray photoresist SAL 605 (The Shipley Co.); APEX-E (IBM Corp.); and an experimental, 193 nm resist, XP96545-7A (The Shipley Co.). These comparison experiments were done under CF4 and Cl2 reactive ion etch conditions. The plasma etch rate of PMMA decreased linearly with concentration of [60]Fullerenes in the film up to at least 11 wt %. When 10.8 wt % C60 (≈7.3 vol %) versus total solids were added to PMMA, the etch rate ratio to SAL 605 dropped from 1.80 to 1.38 in CF4 and from 2.5 to 1.55 in Cl2. Improvements in etch res...

Quantification of the extent of reaction in a negative, novolac-based, chemically amplified resist

Abstract: A technique for determining the extent of reaction and the molar absorptivity of the Fourier transform infrared (FTIR) peak created during the postexposure bake (PEB) reaction of the negative e-beam/x-ray Shipley resist, SAL 605, is described. Wafers were oven baked within a gas-tight bomb. The product of the linking reaction, methanol, was quantified from the gas in the bomb and within the resist film after the PEB. The ether peak, corresponding to the reaction between hexamethoxymethylmelamine (HMMM) and novolac was measured on the same wafer using FTIR. In addition, the absolute number of HMMM molecules reacted was measured by gel permeation chromatography to yield the number of moles methanol produced/HMMM reacted. The molar absorptivity for the ether peak, resulting from a reaction between an HMMM and a phenolic site on the novolac is 3.14±0.53×105 cm2/mole. Under conditions sufficient for imaging in a 0.5 μm thick film, the average number of reactions/HMMM molecule is 1.27±0.24. From previous work o...

High-power, compact, high-efficiency, fiber laser source around 1.24 /spl mu/m for pumping Raman amplifiers

Abstract: Here we describe an extremely compact, high wall plug efficiency, wavelength flexible all-fiber source around 1.24 /spl mu/m, which should find immediate application for pumping fiber Raman amplifier at 1.3 /spl mu/m and we demonstrate its application to distributed Raman amplification.

Novel ultrafast tunable solid state lasers for real-world applications including medical imaging

Abstract: This paper reviews ultrafast Kerr Lens Mode-locked solid- state lasers with particular emphasis on all-solid-state diode-pumped laser technology which has the potential to provide low-cost compact devices for ultrafast instrumentation, particularly for biomedical applications.We have demonstrated the use of ultrafast solid-state lasers for 3D imaging through turbid media using time-gated photorefractive holography, and for fluorescence lifetime imaging.

Chromatic dispersion measurement in the 1-2 /spl mu/m spectral region using a high brightness supercontinuum fiber laser source

Abstract: We demonstrate a novel, diode-pumped ytterbium-doped fiber laser, which combines the unique characteristics of a high brightness supercontinuum together with simplicity of operation and compactness for application in dispersion measurement using both time delay and interferometric techniques and has considerable potential for implementation into a simple yet highly practical apparatus for dispersion measurement. The high brightness and intensity of the source is particularly applicable to nondestructive dispersion-distribution measurements as well as real time control of dispersion during fiber drawing. The potential of these have been examined.

True digital control of interurban traffic networks

Abstract: In this paper, automatic control strategies using a digital control approach are applied to a nonlinear statistical traffic model on the Amsterdam ring road system. Adaptive control systems are coordinated with the following three categories of control: ramp metering variable speed signs, and variable message signs.

A novel optical pulse compressor with use of a comb-like dispersion profiled fiber

Abstract: Electroabsorption modulators (EAM) are proving to be very attractive pulse sources for high bit-rate communications systems

Fuzzy-logic controller synthesis based on sinusoidal-input describing functions and optimization

Abstract: We present a new method for the synthesis of fuzzy-logic controllers (FLCs) for amplitude-sensitive nonlinear plants based on sinusoidal-input describing-function methods plus step-response optimization. This technique exploits the fact that two traditional classes of FLCS are, in functional terms, of the PD and PI types. This method involves a two-step process wherein an initial controller is obtained via the direct generation of the membership functions and output levels based on the "frequency response" of the nonlinear plant in the describing-function sense, then the FLC is perfected via optimization of the step responses for a specified set of input amplitudes. The resulting fuzzy-logic controller obtained includes derivative action in an inner-loop feedback path and nonlinear PI compensation in the forward path; the performance of the closed-loop system is, by design, quite insensitive to reference-input amplitude. This approach is capable of treating nonlinear systems of a very general nature, with no restrictions as to system order, number of nonlinearities, configuration, or nonlinearity type.

MATLAB tools for linear and nonlinear system stability theorem implementation

Abstract: Three MATLAB-based tools have been developed for the convenient assessment of stability conditions for linear and nonlinear systems. The first is a more helpful and definitive version of Nyquist, which has features of automatic zooming (to show all crossings of the real axis and thus display the corresponding critical gain points) and which displays on the real axis a numeral ('0', '1', etc.) that represents the number of unstable (right-half plane) poles that will occur in a closed-loop system with feedback gain k if the point -1/k is located in that region. The second tool is built on this extended Nyquist command, and makes the application of the nonlinear time-varying system circle criterion equally simple and definitive. Finally, a Popov criterion tool is included to achieve better sector bounds for the nonlinear time-invariant case. Examples are presented to show the efficacy of these extensions within the MATLAB environment.