8,032 research outputs found
The transformation of external harmonic series under a translation of origin
Transformation properties of coordinates in inverse power spherical harmonic expansion
Genetic algorithms: a pragmatic, non-parametric approach to exploratory analysis of questionnaires in educational research
Data from a survey to determine student attitudes to their courses are used as an example to show how genetic algorithms can be used in the analysis of questionnaire data. Genetic algorithms provide a means of generating logical rules which predict one variable in a data set by relating it to others. This paper explains the principle underlying genetic algorithms and gives a non-mathematical description of the means by which rules are generated. A commercially available computer program is used to apply genetic algorithms to the survey data. The results are discussed
Evaluation of a Phosphate Management Protocol to Achieve Optimum Serum Phosphate Levels in Hemodialysis Patients
Original article can be found at: http://www.sciencedirect.com/science/journal/10512276 Copyright National Kidney Foundation, Inc. DOI: 10.1053/j.jrn.2008.05.003To evaluate the effectiveness of a protocol designed to optimize serum phosphate levels in patients undergoing regular hemodialysis (HD).Peer reviewe
Individualisation of time-motion analysis : a method comparison and case report series
© Georg Thieme Verlag KG. This study compared the intensity distribution of time-motion analysis data, when speed zones were categorized by different methods. 12 U18 players undertook a routine battery of laboratory- and field-based assessments to determine their running speed corresponding to the respiratory compensation threshold (RCT), maximal aerobic speed (MAS), maximal oxygen consumption (vVO 2max ) and maximal sprint speed (MSS). Players match-demands were tracked using 5 Hz GPS units in 22 fixtures (50 eligible match observations). The percentage of total distance covered running at high-speed (%HSR), very-high speed (%VHSR) and sprinting were determined using the following speed thresholds: 1) arbitrary; 2) individualised (IND) using RCT, vVO 2max and MSS; 3) individualised via MAS per se; 4) individualised via MSS per se; and 5) individualised using MAS and MSS as measures of locomotor capacities (LOCO). Using MSS in isolation resulted in 61 % and 39 % of player's % HSR and % VHSR, respectively, being incorrectly interpreted, when compared to the IND technique. Estimating the RCT from fractional values of MAS resulted in erroneous interpretations of % HSR in 50 % of cases. The present results suggest that practitioners and researchers should avoid using singular fitness characteristics to individualise the intensity distribution of time-motion analysis data. A combination of players' anaerobic threshold, MAS, and MSS characteristics are recommended to individualise player-tracking data
A Delay-Discounting Primer
Given the importance of research findings and the potential of further research to aid in the prediction and control of impulsivity, the primary focus of this chapter (and this book) is on choice and the failure of future events to affect current decisions. In this primer chapter, we consider two types of impulsive choice: (a) preferring a smaller-sooner reward while forgoing a larger-later one and (b) preferring a larger-later aversive outcome over a smaller-sooner one. The first of these is exemplified by the toy-pilfering child with whom we opened this chapter. Taking the toy is immediately rewarded, but it is a short-lived reward because the caretaker soon returns the toy to the victimized peer. Undoubtedly, the child would prefer to play with the toy for a longer period of time, but waiting until the toy is dropped by the peer seems a weak reinforcer when compared with brief access now. To put an economic term on this phenomenon, the child appears to have discounted the value of the delayed but otherwise preferred reward. Delay discounting describes the process of devaluing behavioral outcomes, be they rewarding or aversive events, that happen in the future (and perhaps the past; see chap. 7, this volume). This chapter provides a primer in delay discounting; it is intended for readers who have only a limited background in the procedures, measures, and outcomes of studies examining this form of impulsive choice. Following an overview of the delay-discounting process, its quantification, and its implications for the human condition, emphasis is placed on procedures (and critiques of these procedures). The remainder of the book is concerned with experimental findings, and for the most part, we do not review these here
Reactive ion etching of tellurite and chalcogenide waveguides using hydrogen, methane, and argon
The authors report in detail on the reactive plasma etching properties of tellurium and demonstrate a high quality etching process using hydrogen, methane, and argon. Very low loss planar ridge waveguides are demonstrated. Optical losses in tellurium dioxide waveguides below 0.1 dB/cm in most of the near infrared region of the electromagnetic spectrum and at 1550 nm have been achieved—the lowest ever reported by more than an order of magnitude and clearly suitable for planar integrated devices. The etch process is also shown to be suitable for chalcogenide glasses which may be of importance in applications such as phase change memory devices and nonlinear integrated optics.The support of the Australian Research Council through
its Discovery Grant Program is gratefully acknowledged
Grant No. DP070333
Effect of low-Raman window position on correlated photon-pair generation in a chalcogenide Ge11.5As24Se64.5 nanowire
We investigated correlated photon-pair generation via spontaneous four-wave mixing in an integrated chalcogenideGe11.5As24Se64.5photonicnanowire. The coincidence to accidental ratio, a key measurement for the quality of correlated photon-pair sources, was measured to be only 0.4 when the photon pairs were generated at 1.9 THz detuning from the pump frequency due to high spontaneous Raman noise in this regime. However, the existence of a characteristic low-Raman window at around 5.1 THz in this material's Raman spectrum and dispersion engineering of the nanowire allowed us to generate photon pairs with a coincidence to accidental ratio of 4.5, more than 10 times higher than the 1.9 THz case. Through comparing the results with those achieved in chalcogenide As2S3waveguides which also exhibit a low Raman-window but at a larger detuning of 7.4 THz, we find that the position of the characteristic low-Raman window plays an important role on reducing spontaneous Raman noise because the phonon population is higher at smaller detuning. Therefore the ultimate solution for Raman noise reduction in Ge11.5As24Se64.5 is to generate photon pairs outside the Raman gain band at more than 10 THz detuning
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