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Integration Time (integration + time)
Selected AbstractsRain rate conversion for various integration time for equatorial and tropical climatesINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2008J. S. Mandeep Abstract Rain rate statistics are derived on the basis of rain gauge recordings having effective integration times of 5,min or more. The conversion of such data to equivalent statistics for an effective integration time of 1,min is important to the design of both terrestrial and earth-space microwave systems. Tipping bucket precipitation records for seven locations in South East Asia countries have been analysed and present the results of a testing activity performed on four conversion methods of rain rate integration time, from 5, 10, 30 and 60 to 1,min. Copyright © 2008 John Wiley & Sons, Ltd. [source] Generalization of multivariate optical computations as a method for improving the speed and precision of spectroscopic analysesJOURNAL OF CHEMOMETRICS, Issue 6 2008Marc K. Boysworth Abstract Multivariate optical computations (MOCs) offer improved analytical precision and increased speed of analysis via synchronous data collection and numerical computation with scanning spectroscopic systems. The improved precision originates in the redistribution of integration time from spurious channels to informative channels in an optimal manner for increasing the signal-to-noise ratio with multivariate analysis under the constraint of constant total analysis time. In this work, MOCs perform the multiplication and addition steps of spectral processing by adjusting the integration parameters of the optical detector or adjusting the scanning profile of the tunable optical filter. Improvement in the precision of analysis is achieved via the implicit optimization of the analytically useful signal-to-noise ratio. The speed improvements are realized through simpler data post-processing, which reduces the computation time required after data collection. Alternatively, the analysis time may be significantly truncated while still seeing an improvement in the precision of analysis, relative to competing methods. Surface plasmon resonance (SPR) spectroscopic sensors and visible reflectance spectroscopic imaging were used as test beds for assessing the performance of MOCs. MOCs were shown to reduce the standard deviation of prediction by 15% compared to digital data collection and analysis with the SPR and up to 45% for the imaging applications. Similarly, a 30% decrease in the total analysis time was realized while still seeing precision improvements. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nanometre localization of single ReAsH moleculesJOURNAL OF MICROSCOPY, Issue 3 2004H. PARK Summary ReAsH is a red-emitting dye that binds to the unique sequence Cys-Cys-Xaa-Xaa-Cys-Cys (where Xaa is a noncysteine amino acid) in the protein. We attached a single ReAsH to a calmodulin with an inserted tetracysteine motif and immobilized individual calmodulins to a glass surface at low density. Total internal reflection fluorescence microscopy was used to image individual ReAsH molecules. We determined the centre of the distribution of photons in the image of a single molecule in order to determine the position of the dye within 5 nm precision and with an image integration time of 0.5 s. The photostability of ReAsH was also characterized and observation times ranging from several seconds to over a minute were observed. We found that 2-mercaptoethanesulphonic acid increased the number of collected photons from ReAsH molecules by a factor of two. Individual ReAsH molecules were then moved via a nanometric stage in 25 or 40 nm steps, either at a constant rate or at a Poisson-distributed rate. Individual steps were clearly seen, indicating that the observation of translational motion on this scale, which is relevant for many biomolecular motors, is possible with ReAsH. [source] A search for starlight reflected from HD 75289bMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2003Christopher Leigh ABSTRACT We have used a Doppler tomographic analysis to conduct a deep search for the starlight reflected from the planetary companion to HD 75289. In four nights on VLT(UT2)/UVES in 2003 January, we obtained 684 high-resolution echelle spectra with a total integration time of 26 h. We establish an upper limit on the geometric albedo of the planet p < 0.12 (to the 99.9 per cent significance level) at the most probable orbital inclination i, 60°, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp= 1.6 RJup. We are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks. [source] Determination of nickel, calcium and magnesium in xylem sap by flame atomic absorption spectrometry using a microsampling techniquePHYTOCHEMICAL ANALYSIS, Issue 5 2009Sheila Alves Abstract Introduction Knowledge of xylem sap chemical composition is important to the understanding of translocation, detoxification and tolerance mechanisms. However, the small amount of sample available often hampers its characterisation. Hence, low volume consumption techniques are needed for xylem sap analysis. Objective To develop a microsampling technique for the determination of elements in xylem sap from different plants by flame atomic absorption spectrometry (FAAS). Methodology The microsampling device was optimised in terms of sample volume and integration time. The analytical characteristics of the microsampling technique (µ -FAAS) were established and compared with those of FAAS with traditional continuous nebulisation. The method was validated by means of an independent technique. Results Ca, Mg and Ni were determined in a 50 µL aliquot of xylem sap solution/element that was introduced directly into the flame via the microsampling accessory. Good precision was obtained with relative standard deviations of 1.1, 0.6 and 2.3% for Ca, Mg and Ni, respectively. Matrix effects resulting from the physical characteristics of the samples and possible chemical interferences caused by phosphate and/or sulphate were ruled out. Conclusion A simple, rapid and reproducible microsampling technique coupled to FAAS was developed and successfully applied in the determination of Ca, Mg and Ni in xylem sap. Copyright © 2009 John Wiley & Sons, Ltd. [source] A Novel System for Spectral Analysis of Solar Radiation within a Mixed Beech-Spruce StandPLANT BIOLOGY, Issue 2 2002H. Reitmayer Abstract: A multi-sensor system is described, based on a 1024 channel diode array spectrometer, to measure spectral radiant flux density in the range of 380 nm to 850 nm, with a resolution of 0.8 nm in minimal 16 milliseconds integration time per sensor (noon, clear sky conditions). 264 space-integrating 4, sensors deployed in the canopies and 2 m above stand floor are sequentially connected to the spectrometer by means of 30-m long fibre optics. During low-level conditions (dawn, overcast sky) the system automatically lengthens the integration time of the spectrometer. About 3 sec per sensor, i.e., 13 min for the total of 264 sensors (worst case) are needed to collect spectral energy data, store them on hard disk and move the channel multiplexer to the next fibre optic position. The detection limit of quartz fibre sensors is 0.2 W/m2; precision and absolute error of radiant flux density are smaller than 3 % and 10 %, respectively. The system, operating since 1999, is derived from a 20-sensor pilot system developed for PAR measurements (PMMA fibre sensor, 400nm to 700 nm). Data achieved with the system serve to determine vertical profiles of wavelength dependent radiation extinction, with special respect to R/FR ratios and to develop a model of spectral radiation distribution in a mature forest stand, prerequisites for the computation of carbon gain of the stand and the evaluation of stand growth models. [source] Bone Response to Implant-Supported Frameworks with Differing Degrees of Misfit Preload: In Vivo Study in RabbitsCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 3 2000Torsten Jemt DDS ABSTRACT Purpose: To study the bone response around implants placed in tibia of rabbits that supported misfitting superstructures secured with different degrees of preload. Materials and Methods: Twelve rabbits were provided with two terminal 10-mm and one intermediate 7-mm-long implant in each tibia. After an integration time of about 9 weeks, nine of the animals received one control framework each (n = 9), designed with good fit to all three implants. In the other tibia of these animals, and in both tibias in the remaining three rabbits, test frameworks (n = 15) were connected with a vertical misfit of about 1 mm to the intermediate implant. The intermediate set screws were tightened with a torque ranging from 15 Ncm to 26 Ncm in the different test frameworks. The fascia and skin was then sutured back over the implants. After a loading period of 2 to 3 weeks, the animals were sacrificed, and histomorphometric measurements were made and correlated to the different levels of preload of the central implant. Results: The mean bone-to-metal contact for the three best consecutive threads of the central implant was 40% for both test and control sites (p > .05). Compared to the other regions of the implant thread, less bone-to-metal contact was found at the tip of the test implant threads in the low preload group (p < .05). However, the same relation was not observed in the high preload group. A significant correlation was observed between increasing degree of preload in the central screw joint and increasing bone-to-metal contact, most obviously noticed at the tip of the implant thread (p < .01). Conclusions: Misfit stress levels of clinical magnitudes do not seem to jeopardize osseointegration per se. On the contrary, clinical levels of preload stress seem to significantly promote bone remodeling at the tip of the implant thread. [source] Simulation of two-dimensional turbulent flows in a rotating annulusINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2004Brian D. Storey Abstract Rotating water tank experiments have been used to study fundamental processes of atmospheric and geophysical turbulence in a controlled laboratory setting. When these tanks are undergoing strong rotation the forced turbulent flow becomes highly two dimensional along the axis of rotation. An efficient numerical method has been developed for simulating the forced quasi-geostrophic equations in an annular geometry to model current laboratory experiments. The algorithm employs a spectral method with Fourier series and Chebyshev polynomials as basis functions. The algorithm has been implemented on a parallel architecture to allow modelling of a wide range of spatial scales over long integration times. This paper describes the derivation of the model equations, numerical method, testing and performance of the algorithm. Results provide reasonable agreement with the experimental data, indicating that such computations can be used as a predictive tool to design future experiments. Copyright © 2004 John Wiley & Sons, Ltd. [source] Rain rate conversion for various integration time for equatorial and tropical climatesINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2008J. S. Mandeep Abstract Rain rate statistics are derived on the basis of rain gauge recordings having effective integration times of 5,min or more. The conversion of such data to equivalent statistics for an effective integration time of 1,min is important to the design of both terrestrial and earth-space microwave systems. Tipping bucket precipitation records for seven locations in South East Asia countries have been analysed and present the results of a testing activity performed on four conversion methods of rain rate integration time, from 5, 10, 30 and 60 to 1,min. Copyright © 2008 John Wiley & Sons, Ltd. [source] Simultaneous Raman micro,spectroscopy of optically trapped and stacked cellsJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2007P. R. T. Jess Abstract The combination of Raman spectroscopy and optical trapping holds great promise for single-cell studies and is an emergent theme in microfluidic environments. Here, the evolution of the Raman signal intensity with an axial increment of the mass of the substance of interest inside a specific Raman excitation volume is investigated. Whilst Raman spectroscopy may be applied to tissue samples, solutions and single cells, there are no easily available methods to rapidly acquire signals from small cell populations. We show a simple but powerful method to record the Raman intensity signal simultaneously from a small number of trapped cells or colloidal particles using the technique of optical stacking. The Raman spectra of stacks of red blood cells and yeast cells show that this method can be applied to biological systems. We demonstrate how we may reveal biochemical fingerprints that would otherwise require long integration times for each single cell or averaging over many sequentially acquired cell spectra. There is potential to apply this method to directly attain Raman spectra from sorted sub-populations of normal, abnormal and tumour cell lines. Copyright © 2007 John Wiley & Sons, Ltd. [source] The impact of stellar oscillations on doppler velocity planet searchesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008S. J. O'Toole ABSTRACT We present a quantitative investigation of the effect of stellar oscillations on Doppler velocity planet searches. Using data from four asteroseismological observation campaigns, we find a power-law relationship between the noise impact of these oscillations on Doppler velocities and both the luminosity-to-mass of the target stars, and observed integration times. Including the impact of oscillation, jitter should improve the quality of Keplerian fits to Doppler velocity data. The scale of the effect these oscillations have on Doppler velocity measurements is smaller than that produced by stellar activity, but is most significant for giant and subgiant stars, and at short integration times (i.e. less than a few minutes). Such short observation times tend to be used only for very bright stars. However, since it is these very same stars that tend to be targeted for the highest precision observations, as planet searches probe to lower and lower planet masses, oscillation noise for these stars can be significant and needs to be accounted for in observing strategies. [source] | ||||||||||||||||