Showing papers by "James Taylor published in 2010"

Predictions for the Rates of Compact Binary Coalescences Observable by Ground-based Gravitational-wave Detectors

Abstract: We present an up-to-date, comprehensive summary of the rates for all types of compact binary coalescence sources detectable by the Initial and Advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters, and are still uncertain The most confident among these estimates are the rate predictions for coalescing binary neutron stars which are based on extrapolations from observed binary pulsars in our Galaxy These yield a likely coalescence rate of 100 per Myr per Milky Way Equivalent Galaxy (MWEG), although the rate could plausibly range from 1 per Myr per MWEG to 1000 per Myr per MWEG We convert coalescence rates into detection rates based on data from the LIGO S5 and Virgo VSR2 science runs and projected sensitivities for our Advanced detectors Using the detector sensitivities derived from these data, we find a likely detection rate of 002 per year for Initial LIGO-Virgo interferometers, with a plausible range between 00002 and 02 per year The likely binary neutron-star detection rate for the Advanced LIGO-Virgo network increases to 40 events per year, with a range between 04 and 400 per year

Supercontinuum Generation in Optical Fibers

Abstract: 1. Introduction and history J. R. Taylor 2. Supercontinuum generation in microstructure fiber - an historical note J. K. Ranka 3. Nonlinear fiber optics overview J. C. Travers, M. H. Frosz and J. M. Dudley 4. Fiber supercontinuum generation overview J. M. Dudley 5. Silica fibers for supercontinuum generation J. C. Knight and W. Wadsworth 6. Supercontinuum generation and nonlinearity in soft glass fibers J. H. V. Price and D. J. Richardson 7. Increasing the blue-shift of a picosecond pumped supercontinuum M. H. Frosz, P. M. Moselund, P. D. Rasmussen, C. L. Thomsen and O. Bang 8. Continuous wave supercontinuum generation J. C. Travers 9. Theory of supercontinuum and interactions of solitons with dispersive waves D. V. Skryabin and A. V. Gorbach 10. Interaction of four-wave mixing and stimulated Raman scattering in optical fibers S. Coen, S. G. Murdoch and F. Vanholsbeeck 11. Nonlinear optics in emerging waveguides: revised fundamentals and implications S. V. Afshar, M. Turner and T. M. Monro 12. Supercontinuum generation in dispersion varying fibers G. Genty 13. Supercontinuum generation in chalcogenide glass waveguides Dong-Il Yeom, M. R. E. Lamont, B. Luther Davies and B. J. Eggleton 14. Supercontinuum generation for carrier-envelope phase stabilization of mode-locked lasers S. T. Cundiff 15. Biophotonics applications of supercontinuum generation C. Dunsby and P. M. W. French 16. Fiber sources of tailored supercontinuum in nonlinear microspectroscopy and imaging A. M. Zheltikov Index.

Use of Supplemental Vitamin D Among Infants Breastfed for Prolonged Periods

Abstract: OBJECTIVES: To determine the rate of vitamin D supplementation in predominantly breastfed children. To identify patient characteristics, parental beliefs, and practitioner policies associated with supplementation. METHODS: A prospective observational study was conducted in a practice-based research network. Network pediatricians completed a survey regarding their policy on vitamin D supplementation for breastfed infants. Parents of children 6 to 24 months old completed a survey on the initial type of feeding given to the child, length of breastfeeding, formula supplementation, and use of multivitamins. Parents indicated their level of agreement with statements regarding vitamin D supplementation. RESULTS: Among 44 responding pediatricians, 36.4% indicated that they recommended vitamin D supplementation for all breastfed infants. A total of 2364 surveys were completed on age-eligible children; 1140 infants were breastfed for at least 6 months with little or no formula supplementation. The rate of vitamin D use for these infants was 15.9%. Use of vitamin D was significantly associated with parental agreement that their child9s pediatrician recommended supplementation (odds ratio [OR]: 7.8), and that vitamins are unnecessary because breast milk has all needed nutrition (OR: 0.12). Among parents of predominantly breastfed infants who indicated that their child9s doctor recommended vitamin D, 44.6% gave the supplementation to their child. Conversely, 67% of parents agreed that breast milk has all needed nutrition, and only 3% of these parents gave vitamin D to their children. CONCLUSIONS: A minority of breastfed infants received vitamin D supplementation. Educational efforts directed at both physicians and parents are needed to increase compliance with vitamin D supplementation guidelines.

First search for gravitational waves from the youngest known neutron star

Abstract: We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia A. The search coherently analyzes data in a 12-day interval taken from the fifth science run of the Laser Interferometer Gravitational-Wave Observatory. It searches gravitational wave frequencies from 100 to 300 Hz, and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and for different spin-down mechanisms. No gravitational wave signal was detected. Within the range of search frequencies, we set 95% confidence upper limits of 0.7--1.2e-24 on the intrinsic gravitational wave strain, 0.4--4e-4 on the equatorial ellipticity of the neutron star, and 0.005--0.14 on the amplitude of r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes. This is the first gravitational wave search to present upper limits on r-modes.

Search for gravitational-wave inspiral signals associated with short Gamma-Ray Bursts during LIGO's fifth and Virgo's first science run

Abstract: Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [-5, +1) s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U test, we find no evidence for an excess of weak gravitational-wave signals in our sample of GRBs. We exclude neutron star-black hole progenitors to a median 90% CL exclusion distance of 6.7 Mpc.

Bismuth fiber integrated laser mode-locked by carbon nanotubes

Abstract: We demonstrate passive mode-locking of a Bi-doped fiber laser using a nanotube-based saturable absorber. We achieve stable mode-locking in both the all-normal and net anomalous dispersion regimes. Near transform-limited 4.7 ps soliton pulses are generated in the average-soliton regime, with a chirped fiber Bragg grating used for dispersion compensation to retain an all-fiber format.

Identification and significance of sources of spatial variation in grapevine water status

Abstract: Background and Aims: Water stress in grapevines is directly linked to grape quality. Differential vine water management should therefore be strongly linked to the water stress in the vine. To do this, an understanding of the dominant drivers and indicators of vine water status are needed from a sub-block to whole vineyard level. This understanding will help generate effective vine water status models for variable rate irrigation systems. Methods and Results: A vineyard in the south of France was sampled for pre-dawn leaf water potential (ΨPD) at several dates during the growing season for two consecutive years. Sampling was stratified by soil types and relative within-block vegetative expression. A recursive partitioning analysis identified that cultivar had a dominant effect at low water stress, while vegetative expression and then soil unit effects became dominant as water restriction increased. Variance in ΨPD was calculated at difference scales (plant, site, block and vineyard) and Smith's heterogeneity law was used to evaluate the scalar nature of ΨPD variance. Spatial heterogeneity increased as the season and water restriction increased. Conclusion: Variance in ΨPD changed temporally through a season and the dominant drivers/indicators also changed. The opportunity to spatially manage water stress (irrigation) increased as water restriction increased. Significance of the Study: Managing vine water stress helps optimise production and a ΨPD model would be a useful addition to a viticulture decision support system. This study identified how the variance in ΨPD evolved during a season and the best ancillary indicators of ΨPD for spatial and temporal modelling.

A model for the spatial prediction of water status in vines ( Vitis vinifera L.) using high resolution ancillary information

Abstract: This paper establishes and tests a model to extrapolate vine water status spatially across a vineyard block. The proposed spatial model extrapolates predawn leaf water potential (PLWP), measured at a reference location, to other unsampled locations using a linear combination of spatial ancillary information sources (AIS) and the reference measurement. In the model, the reference value accounts for temporal variability and the AIS accounts for spatial variation of vine water status, which enables extrapolation over the whole domain (vine fields in this case) at any time when a reference measurement is made. The spatial model was validated for two fields planted with Syrah and Mourvedre during the seasons 2003–2004 and 2005–2006, respectively, in the south of France. The proposed spatial model significantly improved the prediction of vine water status, especially under conditions of high water restriction (PLWP < −0.4 MPa), compared with a non-spatial model. The model was robust to the choice of reference site. The results also highlighted that AIS pertaining to canopy growth are the most relevant variables for predicting PLWP under these experimental conditions. Preliminary results showed the potential to calibrate the model from a limited number of field measurements, making it a realistic option for adoption in commercial vineyards. The success of the spatial model in improving the quality of prediction of PLWP means it could be incorporated into a decision-support tool to improve irrigation management within a vineyard.

Sampling for High-Resolution Soil Mapping

Abstract: When doing sensing for high-resolution soil mapping, one has to decide on the disposition of the sensor, which is a special case of spatial sampling. To optimise the pattern of measurements, a cost model and a quality model are proposed. The quality model reflects the coverage of the geographic space, and this is illustrated with some practical experiments. Optimisation of sensing patterns is worked out for two different types of sensing equipment. If the sensor variable differs from the target (management or decision) variable, then a model is needed to predict the target variable from the ancillary data. So in that case, one also has to decide how and where to sample for calibration data. This ‘calibration sampling’ differs from ‘sensor sampling’, as now coverage of the predictor space rather than the geographic space is important. In addition, the handling of extremes is an issue here. Existing methods for calibration sampling are reviewed and a suggestion is made for a new approach, based on fuzzy cluster analysis, which might avoid some of the shortcomings of existing methods.

Comparing the Ability of Multiple Soil Sensors to Predict Soil Properties in a Scottish Potato Production System

Abstract: A soil survey with two soil sensors – an electromagnetic induction (EMI) sensor and a gamma radiometer – was conducted on a farm in south-east Scotland. The collected sensor data were used to direct soil sampling on the farm. The soil samples were then regressed against the sensor output to identify how well the sensor output predicted individual soil properties. The gamma radiometer produced better prediction fits in the topsoil than did the EMI sensor; however, the EMI predicted clay content better in the subsoil. Combining the sensor outputs produced improved fits for the topsoil data but not the subsoil. Neither sensor, individually or combined, produced good fits of soil pH. For potato production systems, topsoil properties are the dominant production determinants; thus a gamma radiometer using current configurations would be the preferred sensor in a single-sensor system assuming that all costs were equal. The economics of single vs. multiple sensor surveys is still unclear.

The Utility of Alkaline Phosphatase Measurement as a Screening Test for Rickets in Breast-fed Infants and Toddlers: A Study From the Puget Sound Pediatric Research Network

Abstract: To determine if alkaline phosphatase (AP) levels are a useful screening test for rickets, the authors measured serum AP levels in children 6 to 15 months old who were predominantly breast-fed for >" xbd="1702" xhg="1679" ybd="1238" yhg="1210"/>6 months without vitamin D supplementation. Radiographs were obtained on children with elevated AP levels to determine the presence of rickets. AP levels were obtained on 246 children; levels were elevated in 33 (13.4%). Rickets was present in 4 of 18 children with elevated levels on whom radiographs were obtained. The sensitivity and specificity of AP levels as a test for rickets was maximal at a cutoff value of 552 U/L. Using this cutoff value, the specificity of AP levels as a test for rickets was 97.4%, and the positive predictive value (PPV) was 40.0%. These results suggest that AP levels may be a useful screening test for rickets in children who are breast-fed for prolonged periods without vitamin D supplementation.

Development of a Symptom Score for Clinical Studies to Identify Children With a Documented Viral Upper Respiratory Tract Infection

Abstract: The objective of this study was to develop a symptom scoring system for use in clinical studies that differentiates children with cold symptoms who have an identifiable viral etiology for their upper respiratory tract infection (URI) from those in whom no virus is detected. Nasal swabs for PCR testing for identification of respiratory viruses were obtained on children aged 2-11 y at baseline and when parents thought their child was developing a cold. Parental-recorded severity of specific symptoms in children with and without a documented viral URI were compared. Nasal swabs were obtained on 108 children whose parents reported their child was developing a cold. A viral etiology was identified in 62 of 108 (57.4%) samples. Symptom measures that best differentiated children with a viral etiology from those without were significant runny nose and significant cough on days 1-4 of the illness. A URI symptom score was developed based on these symptoms, with a sensitivity of 81.4%, specificity of 61.9%, and accuracy of 73.3%. Parental impression is only a moderately accurate predictor of viral URI in children. Our URI symptom score provided a more accurate method for identifying children with viral URIs for clinical studies.

Sensitivity to Gravitational Waves from Compact Binary Coalescences Achieved during LIGO's Fifth and Virgo's First Science Run

Abstract: We summarize the sensitivity achieved by the LIGO and Virgo gravitational wave detectors for compact binary coalescence (CBC) searches during LIGO's fifth science run and Virgo's first science run. We present noise spectral density curves for each of the four detectors that operated during these science runs which are representative of the typical performance achieved by the detectors for CBC searches. These spectra are intended for release to the public as a summary of detector performance for CBC searches during these science runs.

Triple Seasonal Methods for Short-term Load Forecasting

Abstract: Online short-term load forecasting is needed for the real-time scheduling of electricity generation. Univariate methods have been developed that model the intraweek and intraday seasonal cycles in intraday load data. Three such methods, shown to be competitive in recent empirical studies, are double seasonal ARMA, an adaptation of Holt-Winters exponential smoothing for double seasonality, and another, recently proposed, exponential smoothing method. In multiple years of load data, in addition to intraday and intraweek cycles, an intrayear seasonal cycle is also apparent. We extend the three double seasonal methods in order to accommodate the intrayear seasonal cycle. Using six years of British and French data, we show that for prediction up to a day-ahead the triple seasonal methods outperform the double seasonal methods, and also a univariate neural network approach. Further improvement in accuracy is produced by using a combination of the forecasts from two of the triple seasonal methods.

A new, practical approach to maintaining an efficient yet acceptably-performing wireless networked control system

Abstract: Wireless networked control systems have begun to gain acceptance during the last decade, due to the increased flexibility and lower costs they promise to provide compared with wired installations. The pace of application has been held back, however, by the reluctance of industry to make the accommodations necessary to allow wireless paths to be incorporated safely in process control loops, thus limiting the potential applications and benefits of wireless systems. Wireless control signals face time delay that may degrade the performance of the control loop or even lead to instability. This time delay depends on the network configuration. The sampling rate also has a great impact on the stability and performance of the closed-loop control system over the communication networks, yet the data rate should be minimized to conserve node battery life. The main goal of this paper is to present and discuss a real-time nonlinear control system approach that (1) checks a proposed network configuration to determine the time delay which the control data packets will encounter, and reject any proposed configuration that would lead to poor closed-loop system performance; and (2) determines the minimum acceptable sampled data rate that does not degrade control loop performance excessively. The jacketed continuous stirred-tank reactor will be presented as a typical application, to illustrate and validate this development.

An integrated testbed for advanced wireless networked control systems technology

Abstract: Wireless sensor networks (WSNs) have gained widespread acceptance during the last decade, largely due to the greatly increased flexibility, lower costs and scalability that they have been shown to provide. The pace of application in the context of wireless networked control systems (WNCSs) has been somewhat impeded, however, by the reluctance of industry to accept the risks of allowing wireless paths to be incorporated in process control loops. The problem is that there are conflicts between maintaining control loop performance, which can be degraded by many factors, such as low data rates, delays in wireless paths, jitter and electromagnetic interference; and the usual objectives in managing a wireless sensor network, namely freedom to configure the network and to adjust data rates at will, to maximize efficiency and to conserve energy consumption in battery-powered network nodes. In the context of developing advanced controls technology for systems with wireless networks in feedback paths there is a strong need for a test environment that can be used to explore all facets of such systems, including potential problems relating to control loop performance and WSN management. We propose to address this requirement by developing a new testbed for research in WNCSs by adding advanced control agents and process simulators from the Intelligent Control and Asset Management or ICAM project to an existing WSN testbed called the Wireless Industrial Sensor Network Testbed for Radio-Harsh Environments or WINTeR. This testbed has been custom developed for oil and gas industrial environments, i.e., it includes features such as electromagnetic interference and complex mul-tipath propagation. The proposed new testbed, hereafter called WINTeR-ICAM, will include the ICAM Supervisor, ICAM Agents and an additional agent to resolve conflicts between maintaining control loop performance and managing the WSN effectively and efficiently, called a WNCS Coordination Agent or WNCSCA. This agent is designed to be part of an intelligent supervisory control system, and to grant the WSN as much latitude in meeting its objectives as possible while maintaining the performance of control loops that incorporate wireless paths, thus adding to the safety and reliability of future WNCSs. Together, the process simulators, ICAM Agents and WINTeR will provide a powerful new environment for research and development of advanced WNCS technology, with WSN hardware and software in the loop; this novel conception is the contribution of this paper.

A safe communication scheme for an intelligent Wireless Networked Control System Coordination Agent

Abstract: Wireless networked control systems have begun to gain acceptance during the last decade, largely due to the increased flexibility and lower costs they promise to provide. The pace of application has been held back, however, by the reluctance of industry to make the accommodations necessary to allow wireless paths to be incorporated in process control loops, thus limiting the potential applications and benefits of wireless systems. The problem is that there are conflicts between maintaining the performance of control loops, which can be degraded by slow data rates and delays in wireless paths, and the usual objectives in managing a wireless sensor network, namely freedom to configure the network and to adjust data rates at will, to maximize efficiency and to conserve energy consumption in the network nodes, which are very often battery powered. We address this conflict by developing a new1 component for use in industrial control systems, called a Wireless Networked Control System Coordination Agent. This agent is designed to be part of an intelligent supervisory control system, and to grant the wireless sensor network gateway as much latitude in meeting its objectives as possible while maintaining the performance of control loops that incorporate wireless paths, thus adding to the safety and reliability of future wireless networked control systems. In this discussion we deal with data rates and control-loop path delays as the two primary concerns; in the future we plan to extend the scope of this agent to handle more issues, such as jitter and wireless sensor network loading effects (e.g., variation of path delays with changes in loading).

Narrow Linewidth Bismuth-Doped All-Fiber Ring Laser

Abstract: We report a novel narrow linewidth Bismuth-doped all-fiber ring laser, operating at 1177 nm. We achieve a 10-mW output in a 4-GHz linewidth, direct from the oscillator under 7 W of pumping, delivered by an Yb-fiber laser. Mode suppression in the 50-m unidirectional ring cavity is provided by a narrowband fiber Bragg grating and two fiber integrated Fabry-Perot (FP) filters. The FP filters provide a factor of 20 mode suppression, while improving the relative intensity noise by up to 20 dB/Hz. The optical signal-to-noise ratio (OSNR) is ~60 dB.

An evaluation of Bayesian techniques for controlling model complexity in a neural network for short-term load forecasting

Abstract: Artificial neural networks have frequently been proposed for electricity load forecasting because of their capabilities for the nonlinear modelling of large multivariate data sets. Modelling with neural networks is not an easy task though; two of the main challenges are defining the appropriate level of model complexity, and choosing the input variables. This paper evaluates techniques for automatic neural network modelling within a Bayesian framework, as applied to six samples containing daily load and weather data for four different countries. We analyse input selection as carried out by the Bayesian 'automatic relevance determination', and the usefulness of the Bayesian 'evidence' for the selection of the best structure (in terms of number of neurones), as compared to methods based on cross-validation.

Analysis of the spatial variability of production attributes in sweet corn.

Abstract: A manual site-directed survey of yield, cob dimensions and plant densities is undertaken across three sweet corn (Zea mays var. rugosa) production fields in Bathurst, New South Wales, Australia, to assess if the spatial variation in production is sufficient to warrant further investment in site-specific studies. The 113 data points are assessed using non-spatial and spatial analysis and the data interpolated and mapped. Non-spatial analysis shows a large magnitude in all variables, particularly yield, which ranges from 6 to 30 Mg ha−1. Spatial analysis shows that all variables have moderate to strong spatial response and the resultant maps show strong spatial patterns that may be conducive to differential management strategies. The observed variation is similar to the variation reported in maize (Zea mays) where site-specific management has been successfully adopted.

Soliton-dispersive wave collisions in high average power supercontinuum generation

Abstract: Experimental and numerical results on the interaction of the Raman-soliton continuum and dispersive waves through inelastic collisions mediated by four wave mixing are presented. In particular the spectral broadening of the continuum to longer wavelengths beyond a second zero dispersion point through four wave mixing of the dispersive wave produced by soliton self-frequency shift cancelation and other solitons in the continuum is considered.

Characterization of saturable absorption of E 11 and E 22 transitions of carbon nanotubes

Abstract: We characterize the saturable absorption properties of the E 11 and E 22 transitions of the same highly-purified film of single-wall carbon-nanotubes, and compare the results in terms of modulation-depth, saturation-intensity and mode-locked fiber laser performance.

Giant chirp oscillators: Modeling and experiment

Abstract: We review recent progress in a class of normally dispersive mode-locked laser that has become known as a giant chirp oscillator. We discuss spectral and temporal versatility and consider the pulse formation dynamics, both using numerical simulation and experimental investigation.

Bismuth-doped fiber integrated ring laser mode-locked with a nanotube-based saturable absorber

Abstract: We demonstrate passive mode-locking of a bismuth-doped fiber laser using a single-wall nanotube-based saturable absorber. Stable operation in the all-normal dispersion and average soliton regime is obtained, with an all-fiber integrated format.

Narrow-line all-fiber bismuth ring laser

Abstract: A narrow-line continuous-wave bismuth-doped all-fiber laser, with 10 mW output power in a 4 GHz linewidth is demonstrated. We use a narrow-band FBG and fiber-integrated Fabry-Perot filters to achieve a factor of 20 mode suppression.