Showing papers by "James Taylor published in 1995"
TL;DR: Tachypnea, as defined in this study, is an important predictive sign of pneumonia in febrile children younger than 2 years and obviates the need for chest radiography in most settings.
Abstract: Objective: To determine values for defining tachypnea in febrile children younger than 2 years that best identify those at risk for pneumonia. Design: Prospective case series. Study Patients: Children younger than 2 years presenting to the emergency department of a children's hospital with a temperature of 38°C or higher. Interventions: Using a standardized method, respiratory rates were obtained on eligible children for 1 year. Study patients were classified as having pneumonia or no pneumonia based on clinical evaluation and chest radiograph findings. Receiver operating characteristic curves were constructed to select the values for respiratory rate that maximized sensitivity and specificity of tachypnea as a sign of pneumonia. Results: Data were analyzed for 572 children; pneumonia was present in 42 (7%). The diagnostic utility of tachypnea was maximal when cutoff values for respiratory rates of 59/min in infants younger than 6 months, 52/min in those aged 6 through 11 months, and 42/min in those aged 1 to 2 years were selected. Based on these definitions, tachypnea as a sign of pneumonia had a sensitivity of 73.8%, specificity of 76.8%, positive predictive value of 20.1%, and negative predictive value of 97.4%. Conclusions: Tachypnea, as defined in this study, is an important predictive sign of pneumonia in febrile children younger than 2 years. Conversely, the absence of tachypnea obviates the need for chest radiography in most settings. (Arch Pediatr Adolesc Med. 1995;149:283-287)
102 citations
TL;DR: Data from this nationally representative sample indicate that if women refrained from smoking while pregnant, up to 30% of SIDS might be prevented.
99 citations
TL;DR: An all-solid-state tunable diode-pumped Cr3+:LiSrAlF 6 (Cr:LiSAF) regenerative amplifier, seeded by a tunable bi-modulus femtosecond oscillator, has been demonstrated for the first time to the authors' knowledge.
Abstract: An all-solid-state tunable diode-pumped Cr3+:LiSrAlF 6 (Cr:LiSAF) regenerative amplifier, seeded by a tunable diode-pumped Cr:LiSAF femtosecond oscillator, has been demonstrated for the first time to our knowledge. The oscillator was tunable over 75 nm and generated pulses as short as 24 fs. As much as 70 mW average output power was obtained with pulses of 40-fs duration. The amplifier produced recompressed pulses of less than 200-fs duration with energies exceeding 1 μJ at a repetition rate as high as 25 kHz.
81 citations
TL;DR: In this article, a 39 dB-gain silica fibre Raman amplifier was demonstrated at 1.3 mu m using a 1064 nm pump and a monolithic ring cavity constructed solely from conventional fiber components.
Abstract: A 39 dB-gain silica fibre Raman amplifier is demonstrated at 1.3 mu m using a 1064 nm pump. Cascaded Raman generation and amplification are achieved in a monolithic ring cavity constructed solely from conventional fibre components, i.e. fusion WDM couplers and standard silica fibre.
51 citations
TL;DR: In this article, a single-frequency unidirectional erbium fiber ring laser operating at 1.55 /spl mu/m was reported, which uses an intracavity phase-shifted fibre Bragg grating as an ultranarrow frequency bandpass filter.
Abstract: The authors report a single-frequency unidirectional erbium fibre ring laser operating at 1.55 /spl mu/m which uses an intracavity phase-shifted fibre Bragg grating as an ultranarrow frequency bandpass filter. The linewidth of the laser was measured to be <2.0 kHz.
40 citations
13 Dec 1995
TL;DR: The second phase of algorithmic implementation of the HSML ideas and language constructs for dealing with state-event handling and model structural changes in continuous-time system components are described.
Abstract: Previous research in the area of modeling and simulation of hybrid systems led to the development of a general hybrid systems modeling language (HSML), part of which was implemented in a preliminary way by extending MATLAB. This paper describes the second phase of algorithmic implementation of the HSML ideas and language constructs for dealing with state-event handling and model structural changes in continuous-time system components. Specifically, the standard MATLAB model framework and integration algorithms are extended to support these phenomena. An example is presented to show the efficacy of these extensions within the MATLAB environment.
38 citations
TL;DR: What is to the authors' knowledge the first Kerr-lens mode locking of the visible transitions at 607 and 639 nm in Pr3+:YLF in optimized all-solid-state laser configurations with thin (<100-μm) colloidally colored CdSeS glasses.
Abstract: We report what is to our knowledge the first Kerr-lens mode locking of the visible transitions at 607 and 639 nm in Pr3+:YLF. Initiation of the self-mode locking took place through the use of liquid saturable absorbers to establish saturation parameters, and it was carried out in optimized all-solid-state laser configurations (but with gas-laser pumping) with thin (<100-μm) colloidally colored CdSeS glasses. Pulse durations were in the range of 8–10 ps.
37 citations
TL;DR: In this article, a totally integrated all-fibre femtosecond chirped pulse amplification scheme was described, which was temporally stretched, amplified in a diode pumped Yb-Er fiber amplifier and recompressed to give 900 fs pulses of 1.6 nJ energy and an average power of 4.8 mW.
Abstract: A totally integrated all-fibre femtosecond chirped pulse amplification scheme is described. Transform-limited 670 fs pulses at a 3.1 MHz repetition rate, derived from a diode pumped Yb-Er figure-of-eight fibre laser, were temporally stretched, amplified in a diode pumped Yb-Er fibre amplifier and recompressed to give 900 fs pulses of 1.6 nJ energy and an average power of 4.8 mW. Chirped Bragg fibre gratings were used to stretch and recompress the pulses, in a novel configuration which minimises loss.
35 citations
TL;DR: In this paper, a nonlinear adiabatic compression of approximately 5 ps pulses generated by a chirp-compensated electroabsorption modulator operating at 10 GHz was demonstrated using dispersiondecreasing fiber.
Abstract: Nonlinear adiabatic compression of transform-limited approximately 5 ps pulses generated by a chirp-compensated electroabsorption modulator operating at 10 GHz is demonstrated using dispersion-decreasing fibre. 200 fs soliton pulses are generated with no pedestal component.
32 citations
TL;DR: An all-solid-state, tunable, diode-pumped Cr:LiSrAlF(6) regenerative amplifier has been demonstrated, for the first time to the authors' knowledge, that amplifies femtosecond pulses to energies exceeding 1 mu;mJ at up to a 16-kHz repetition rate.
Abstract: A tunable femtosecond solid-state amplifier system that uses only 3 W of 488-nm argon-ion pump power has been demonstrated to deliver microjoule pulses at repetition rates up to 20 kHz, with a maximum pulse energy of 14 μJ obtained at 5 kHz. An all-solid-state, tunable, diode-pumped Cr:LiSrAlF6 regenerative amplifier has been demonstrated, for the first time to our knowledge, that amplifies femtosecond pulses to energies exceeding 1 μJ at up to a 16-kHz repetition rate.
26 citations
TL;DR: It is suggested that prior behavioral sensitization to cocaine diminishes the stressful effect of conditioned fear and that these effects are reversed when sensitization is prevented with R-(+)-HA-966.
28 Sep 1995
TL;DR: The standard MATLAB model framework and integration algorithms are extended to support the ideas and language constructs for dealing with state-event handling and vector-field conflicts in continuous-time components.
Abstract: Previous research in the area of modeling and simulation of hybrid systems led to the development of a general hybrid systems modeling language (HSML) that has been described elsewhere. Features of HSML include: hierarchical, modular construction of models from components; consistent yet distinctive definition of continuous-time, discrete-time and logic-based components; prioritized scheduling of discrete-time components; mechanisms for state-event handling; approaches for dealing with vector-field conflicts and changing model order and structure; rigorous type and range checking; and a,strict semantic basis that permits extensive checking and validation of the model. This paper describes a first step towards algorithmic implementation of the HSML ideas and language constructs for dealing with state-event handling and vector-field conflicts in continuous-time components. Specifically, the standard MATLAB model framework and integration algorithms are extended to support these phenomena. An example is presented to show the efficacy of these extensions within the MATLAB environment.
TL;DR: A 10-GHz source of pulse-width-tunable bandwidth-limited optical pulses operating near 1.55 μm based on an electroabsorption modulator and a tunable-dispersion chirped fiber Bragg grating is described both experimentally and theoretically.
Abstract: A 10-GHz source of pulse-width-tunable bandwidth-limited optical pulses operating near 1.55 μm based on an electroabsorption modulator and a tunable-dispersion chirped fiber Bragg grating is described both experimentally and theoretically. The pulse-width range attainable from this device is significantly extended through the exploitation of nonlinear adiabatic solitonlike pulse compression and spectral filtering.
TL;DR: In this paper, transform-limited pulses of 5-6 ps were generated at 10 GHz using an electroabsorption modulator in conjunction with a dispersive transmission filter based on a chirped fibre Bragg grating.
Abstract: Transform-limited pulses of 5-6 ps have been generated at 10 GHz using an electroabsorption modulator in conjunction with a dispersive transmission filter based on a chirped fibre Bragg grating. This method is compact, controllable and incorporates minimal fibre lengths.
TL;DR: A novel, low-insertion-loss transmission with the implementation of linearly chirped fiber Bragg grating reflectors and polarization-splitting fiber fusion couplers is reported, and Pulse chirping, chromatic dispersion compensation, and pulse compression are demonstrated.
Abstract: A novel, low-insertion-loss transmission filter with the implementation of linearly chirped fiber Bragg grating reflectors and polarization-splitting fiber fusion couplers is reported. Pulse chirping, chromatic dispersion compensation, and pulse compression are demonstrated. Cascading of dispersive filters, including application to a low-loss pulse stretcher/recompressor of femtosecond pulses, is also demonstrated.
01 Jan 1995
TL;DR: This paper focuses on solving the failure detection and isolation (fdi) problem by developing a model-based approach using a parity equation implementation of directional residuals, an extension of the generalized parity vector (gpv) technique based on the stable factorization approach.
Abstract: This paper focuses on solving the failure detection and isolation (fdi) problem by developing a model-based approach using a parity equation implementation of directional residuals. This new approach is an extension of the generalized parity vector (gpv) technique based on the stable factorization approach. The present work has improved the approach in Viswanadham, Taylor and Luce [1] in two important respects: (1) isolability has been increased, both in terms of the number of failures isolated and the quality of discrimination; and (2) the robustness of this technique has been increased by incorporating an adaptive fuzzy threshold to the decision-maker block. In the first instance, a novel transformation matrix computation is presented that enhances the isolation properties of the fdi algorithm, i.e., increases the maximum number of faults that can be isolated and the number of disturbances that can be decoupled, above the number of outputs of the system [2]. Robustness is also increased due to the fact that the adaptive fuzzy threshold takes into account the effects of disturbances and modeling errors, due to the deviations of the process from its operational point and possible nonlinear effects. Moreover, disturbance decoupling is implemented in the stable factorization framework to make the residuals immune to disturbance effects. The efficacy and robustness of this technique is demonstratedby designing an fdi scheme for a continuous stirred tank reactor. Subsequently, its performance in a largescale process will be tested using the actual model and data from one of the pilot plant facilities involved in the Petroleum Applications of Wireless Systems (paws) project, sponsored under the Atlantic (Canada) Innovation Fund (aif). References
TL;DR: A double gain section composite cavity for LiSAF microlaser using either 670 nm GalnP/AlGalnP diode laser or krypton ion laser pumping allowed tunable single longitudinal mode operation with detection limited linewidth of less than 20 MHz as mentioned in this paper.
28 Sep 1995
TL;DR: The linear MODA algorithm based on frequency response is being extended to support the synthesis of models of nonlinear systems and uses a describing-function approach to develop an amplitude-dependent characterization of the nonlinear system frequency response.
Abstract: Several model-order deduction algorithms (MODAs) have been developed to coordinate the synthesis of lumped (finite-dimensional), linear system models, of acceptable order, that accurately characterize the behavior of a system over a frequency range of interest (FROI) [/spl omega//sub min/,/spl omega//sub max/]. The most recent of these techniques considers the frequency response of the model as the "performance metric" and systematically increases model complexity until the frequency response over a FROI has converged to within a user-specific tolerance. The linear MODA algorithm based on frequency response is being extended to support the synthesis of models of nonlinear systems. This technique follows a procedure similar to the linear frequency-domain algorithm, but uses a describing-function approach to develop an amplitude-dependent characterization of the nonlinear system frequency response. The extended algorithm synthesizes model that are also of low order; in addition, they include only those nonlinear effects that influence the frequency response significantly over the FROI and for an amplitude range of interest.
TL;DR: In this paper, a femtosecond figure of eight fiber laser was constructed incorporating a dispersion decreasing (tapered) fiber within the nonlinear loop to give rise to intensity (phase) dependent switching and adiabatic compression.
Abstract: A femtosecond figure of eight fibre laser has been constructed incorporating a dispersion decreasing (tapered) fibre within the nonlinear loop to give rise to intensity (phase) dependent switching and adiabatic compression. With system optimisation, it should be possible to achieve femtosecond operation without spectral sideband generation.
TL;DR: In this article, it was demonstrated that reflection gratings with any type of chirp can be written into photosensitive fibres using holographic phase masks. But the length dependence of induced chirps was designed to be linear or quadratic in wavelength.
Abstract: It is demonstrated that reflection gratings with any type of chirp may be written into photosensitive fibres using holographic phase masks. Chirped bandwidths of 5-15 nm have been achieved in 8 mm long gratings with reflectivities up to 98%. The length dependence of the induced chirp was designed to be linear or quadratic in wavelength. Reasonable agreement is shown with theoretical calculations. These gratings have also been used for the first time to re-compress 400 fs pulses broadened to approximately 30 ps after transmission through an optical fibre at 1560 nm. Nearly complete re-compression is observed with a compression ratio of approximately 65.
TL;DR: In this article, a modified figure-of-eight laser with a 70% output coupler inside a nonlinear amplified loop mirror was constructed for propagation experiments in standard telecommunication fibres.
Abstract: The Letter reports on a modified figure-of-eight laser constructed with a 70% output coupler inside a nonlinear amplified loop mirror generating single nearly transform-limited pulses (1.3 ps) per high-power roundtrip ( approximately 35 W). This laser is a convenient source of soliton pulses for propagation experiments in standard telecommunication fibres.
TL;DR: In this paper, a step-chirp, phase masking technique has been used to temporally broaden the 380 fs pulses from an erbium fiber soliton laser operating at 1.56 μm by factors of greater than forty.
TL;DR: In this paper, a nonlinear amplifying loop minor (NALM) was used to recover 1.3 ps fundamental soliton pulses (Z/sub 0/ approximately=45 m) following transmission over 5 km of standard telecommunications fibre.
Abstract: A nonlinear amplifying loop minor (NALM) has been used to recover 1.3 ps fundamental soliton pulses (Z/sub 0/ approximately=45 m) following transmission over 5 km of standard telecommunications fibre. The recovery has been examined as a function of the gain within the NALM. >
TL;DR: Soliton evolution in optical fibers and all-optical soliton recovery with a nonlinear active loop mirror has been studied with view to applications in transmission systems having a high bit-rate-]distance product.
Abstract: Soliton evolution in optical fibers and all-optical soliton recovery with a nonlinear active loop mirror have been studied with view to applications in transmission systems having a high bit-rate–distance product. A 1.3-ps pulse is successfully transmitted over 111 soliton periods, reshaped, amplified, and transmitted another 111 soliton periods.
TL;DR: A simple technique for the generation of transform-limited pulses with durations of a few picoseconds at low repetition rates is reported and 6 ps pulses are generated at 1 and 2 GHz.
Abstract: A simple technique for the generation of transform-limited pulses with durations of a few picoseconds at low repetition rates is reported. This is demonstrated experimentally and 6 ps pulses are generated at 1 and 2 GHz. These pulse trains have very low duty cycles and background levels.
TL;DR: In this paper, the authors demonstrate the generation of transform-limited optical pulses with low background levels and durations tunable in the range 1 -2 ps at readily selectable low base rates of 1-2.5 GHz.
Abstract: The authors demonstrate the generation of transform-limited optical pulses with low background levels and durations tunable in the range 1-2 ps at readily selectable low base rates of 1-2.5 GHz. The system described is simple, compact and suitable for multiplexing up to 100 Gbit/s per channel.
TL;DR: In this paper, the authors used self-mode-locking initiated by synchronous pumping of a c.w. Cr4+ : YAG laser to generate tuneable pulses of about 100fs duration.
Abstract: Wavelength tuneable pulses of about 100fs duration have been generated through self-mode-locking initiated by synchronous pumping of a c.w. Cr4+ : YAG laser.
Proceedings Article•
21 May 1995
TL;DR: In this paper, a compact Cr4+:YAG tunable solid state laser pump source operating around 148 µm has been used to pump an Er3+ fiber laser and amplifier.
Abstract: A compact Cr4+:YAG tunable solid state laser pump source operating broadly around 148 µm has been used to pump an Er3+ fibre laser and amplifier The laser exhibited a 55% slope efficiency and output powers in excess of 21 dBm At 155 µm, the amplifier had a measured gain of 25 dB for a launched pump power of 236 dBm Increased power scaling should be readily achieved
30 Jan 1995
TL;DR: In this paper, the authors report the application to dispersion correction of a simple yet novel low insertion loss, polarisation independent, all-fibre transmission filter incorporating chirped Bragg reflectors.
Abstract: The authors report the application to dispersion correction of a simple yet novel low insertion loss, polarisation independent, all-fibre transmission filter incorporating chirped Bragg reflectors. Implementing this filter, they overcome the problem of high insertion loss associated with grating application, i.e. chirped gratings operate in reflection, so in order to recover the reflected radiation they are used in conjunction with a 50:50 coupler, incurring a signal loss of at least 6 dB. The dispersion correction has been demonstrated at 112 Gbit/s (470 fs pulses) and pulse width recovery with a figure of merit as high as 0.9 has been achieved in propagating over 3.9 km of dispersion shifted fibre or 260 m of standard telecommunications fibre. The authors have also demonstrated that it is possible to cascade the chirped grating transmission filters with little degradation in the figure of merit for pulse recovery.