Parameters Describing Earth Observing Remote Sensing Systems
NASA Technical Reports Server (NTRS)
Zanoni, Vicki; Ryan, Robert E.; Pagnutti, Mary; Davis, Bruce; Markham, Brian; Storey, Jim
2003-01-01
The Earth science community needs to generate consistent and standard definitions for spatial, spectral, radiometric, and geometric properties describing passive electro-optical Earth observing sensors and their products. The parameters used to describe sensors and to describe their products are often confused. In some cases, parameters for a sensor and for its products are identical; in other cases, these parameters vary widely. Sensor parameters are bound by the fundamental performance of a system, while product parameters describe what is available to the end user. Products are often resampled, edge sharpened, pan-sharpened, or compressed, and can differ drastically from the intrinsic data acquired by the sensor. Because detailed sensor performance information may not be readily available to an international science community, standardization of product parameters is of primary performance. Spatial product parameters described include Modulation Transfer Function (MTF), point spread function, line spread function, edge response, stray light, edge sharpening, aliasing, ringing, and compression effects. Spectral product parameters discussed include full width half maximum, ripple, slope edge, and out-of-band rejection. Radiometric product properties discussed include relative and absolute radiometry, noise equivalent spectral radiance, noise equivalent temperature diffenence, and signal-to-noise ratio. Geometric product properties discussed include geopositional accuracy expressed as CE90, LE90, and root mean square error. Correlated properties discussed include such parameters as band-to-band registration, which is both a spectral and a spatial property. In addition, the proliferation of staring and pushbroom sensor architectures requires new parameters to describe artifacts that are different from traditional cross-track system artifacts. A better understanding of how various system parameters affect product performance is also needed to better ascertain the
The variance needed to accurately describe jump height from vertical ground reaction force data.
Richter, Chris; McGuinness, Kevin; O'Connor, Noel E; Moran, Kieran
2014-12-01
In functional principal component analysis (fPCA) a threshold is chosen to define the number of retained principal components, which corresponds to the amount of preserved information. A variety of thresholds have been used in previous studies and the chosen threshold is often not evaluated. The aim of this study is to identify the optimal threshold that preserves the information needed to describe a jump height accurately utilizing vertical ground reaction force (vGRF) curves. To find an optimal threshold, a neural network was used to predict jump height from vGRF curve measures generated using different fPCA thresholds. The findings indicate that a threshold from 99% to 99.9% (6-11 principal components) is optimal for describing jump height, as these thresholds generated significantly lower jump height prediction errors than other thresholds. PMID:25010220
Gay, Guillaume; Courtheoux, Thibault; Reyes, Céline
2012-01-01
In fission yeast, erroneous attachments of spindle microtubules to kinetochores are frequent in early mitosis. Most are corrected before anaphase onset by a mechanism involving the protein kinase Aurora B, which destabilizes kinetochore microtubules (ktMTs) in the absence of tension between sister chromatids. In this paper, we describe a minimal mathematical model of fission yeast chromosome segregation based on the stochastic attachment and detachment of ktMTs. The model accurately reproduces the timing of correct chromosome biorientation and segregation seen in fission yeast. Prevention of attachment defects requires both appropriate kinetochore orientation and an Aurora B–like activity. The model also reproduces abnormal chromosome segregation behavior (caused by, for example, inhibition of Aurora B). It predicts that, in metaphase, merotelic attachment is prevented by a kinetochore orientation effect and corrected by an Aurora B–like activity, whereas in anaphase, it is corrected through unbalanced forces applied to the kinetochore. These unbalanced forces are sufficient to prevent aneuploidy. PMID:22412019
Cimpoesu, Dorin Stoleriu, Laurentiu; Stancu, Alexandru
2013-12-14
We propose a generalized Stoner-Wohlfarth (SW) type model to describe various experimentally observed angular dependencies of the switching field in non-single-domain magnetic particles. Because the nonuniform magnetic states are generally characterized by complicated spin configurations with no simple analytical description, we maintain the macrospin hypothesis and we phenomenologically include the effects of nonuniformities only in the anisotropy energy, preserving as much as possible the elegance of SW model, the concept of critical curve and its geometric interpretation. We compare the results obtained with our model with full micromagnetic simulations in order to evaluate the performance and limits of our approach.
Elvira, L; Hernandez, F; Cuesta, P; Cano, S; Gonzalez-Martin, J-V; Astiz, S
2013-06-01
Although the intensive production system of Lacaune dairy sheep is the only profitable method for producers outside of the French Roquefort area, little is known about this type of systems. This study evaluated yield records of 3677 Lacaune sheep under intensive management between 2005 and 2010 in order to describe the lactation curve of this breed and to investigate the suitability of different mathematical functions for modeling this curve. A total of 7873 complete lactations during a 40-week lactation period corresponding to 201 281 pieces of weekly yield data were used. First, five mathematical functions were evaluated on the basis of the residual mean square, determination coefficient, Durbin Watson and Runs Test values. The two better models were found to be Pollott Additive and fractional polynomial (FP). In the second part of the study, the milk yield, peak of milk yield, day of peak and persistency of the lactations were calculated with Pollot Additive and FP models and compared with the real data. The results indicate that both models gave an extremely accurate fit to Lacaune lactation curves in order to predict milk yields (P = 0.871), with the FP model being the best choice to provide a good fit to an extensive amount of real data and applicable on farm without specific statistical software. On the other hand, the interpretation of the parameters of the Pollott Additive function helps to understand the biology of the udder of the Lacaune sheep. The characteristics of the Lacaune lactation curve and milk yield are affected by lactation number and length. The lactation curves obtained in the present study allow the early identification of ewes with low milk yield potential, which will help to optimize farm profitability. PMID:23257242
Madebene, Bruno; Ulusoy, Inga; Mancera, Luis; Scribano, Yohann; Chulkov, Sergey
2011-01-01
Summary We present a theoretical framework for the computation of anharmonic vibrational frequencies for large systems, with a particular focus on determining adsorbate frequencies from first principles. We give a detailed account of our local implementation of the vibrational self-consistent field approach and its correlation corrections. We show that our approach is both robust, accurate and can be easily deployed on computational grids in order to provide an efficient computational tool. We also present results on the vibrational spectrum of hydrogen fluoride on pyrene, on the thiophene molecule in the gas phase, and on small neutral gold clusters. PMID:22003450
Dunn, Nicholas J. H.; Noid, W. G.
2015-12-28
The present work investigates the capability of bottom-up coarse-graining (CG) methods for accurately modeling both structural and thermodynamic properties of all-atom (AA) models for molecular liquids. In particular, we consider 1, 2, and 3-site CG models for heptane, as well as 1 and 3-site CG models for toluene. For each model, we employ the multiscale coarse-graining method to determine interaction potentials that optimally approximate the configuration dependence of the many-body potential of mean force (PMF). We employ a previously developed “pressure-matching” variational principle to determine a volume-dependent contribution to the potential, U{sub V}(V), that approximates the volume-dependence of the PMF. We demonstrate that the resulting CG models describe AA density fluctuations with qualitative, but not quantitative, accuracy. Accordingly, we develop a self-consistent approach for further optimizing U{sub V}, such that the CG models accurately reproduce the equilibrium density, compressibility, and average pressure of the AA models, although the CG models still significantly underestimate the atomic pressure fluctuations. Additionally, by comparing this array of models that accurately describe the structure and thermodynamic pressure of heptane and toluene at a range of different resolutions, we investigate the impact of bottom-up coarse-graining upon thermodynamic properties. In particular, we demonstrate that U{sub V} accounts for the reduced cohesion in the CG models. Finally, we observe that bottom-up coarse-graining introduces subtle correlations between the resolution, the cohesive energy density, and the “simplicity” of the model.
Describing Comprehension: Teachers' Observations of Students' Reading Comprehension
ERIC Educational Resources Information Center
Vander Does, Susan Lubow
2012-01-01
Teachers' observations of student performance in reading are abundant and insightful but often remain internal and unarticulated. As a result, such observations are an underutilized and undervalued source of data. Given the gaps in knowledge about students' reading comprehension that exist in formal assessments, the frequent calls for teachers'…
ACCURATE CHARACTERIZATION OF HIGH-DEGREE MODES USING MDI OBSERVATIONS
Korzennik, S. G.; Rabello-Soares, M. C.; Schou, J.; Larson, T. P.
2013-08-01
We present the first accurate characterization of high-degree modes, derived using the best Michelson Doppler Imager (MDI) full-disk full-resolution data set available. A 90 day long time series of full-disk 2 arcsec pixel{sup -1} resolution Dopplergrams was acquired in 2001, thanks to the high rate telemetry provided by the Deep Space Network. These Dopplergrams were spatially decomposed using our best estimate of the image scale and the known components of MDI's image distortion. A multi-taper power spectrum estimator was used to generate power spectra for all degrees and all azimuthal orders, up to l = 1000. We used a large number of tapers to reduce the realization noise, since at high degrees the individual modes blend into ridges and thus there is no reason to preserve a high spectral resolution. These power spectra were fitted for all degrees and all azimuthal orders, between l = 100 and l = 1000, and for all the orders with substantial amplitude. This fitting generated in excess of 5.2 Multiplication-Sign 10{sup 6} individual estimates of ridge frequencies, line widths, amplitudes, and asymmetries (singlets), corresponding to some 5700 multiplets (l, n). Fitting at high degrees generates ridge characteristics, characteristics that do not correspond to the underlying mode characteristics. We used a sophisticated forward modeling to recover the best possible estimate of the underlying mode characteristics (mode frequencies, as well as line widths, amplitudes, and asymmetries). We describe in detail this modeling and its validation. The modeling has been extensively reviewed and refined, by including an iterative process to improve its input parameters to better match the observations. Also, the contribution of the leakage matrix on the accuracy of the procedure has been carefully assessed. We present the derived set of corrected mode characteristics, which includes not only frequencies, but line widths, asymmetries, and amplitudes. We present and discuss
NASA Astrophysics Data System (ADS)
Bonilla, Jose; Kalwa, Fritz; Händel, Falk; Binder, Martin; Stefan, Catalin
2016-04-01
The Dupuit-Thiem equation is normally used to assess flow towards a pumping well in unconfined aquifers under steady-state conditions. For the formulation of the equation it is assumed that flow is laminar, radial and horizontal towards the well. It is well known that these assumptions are not met in the vicinity of the well; some authors restrict the application of the equation only to a radius larger than 1.5-fold the aquifer thickness. In this study, the equation accuracy to predict the pressure head is evaluated as a simple and quick analytical method to describe the flow pattern for different injection rates in the LSAW. A laboratory scale aquifer-well system (LSAW) was implemented to study the aquifer recharge through wells. The LSAW consists of a 1.0 m-diameter tank with a height of 1.1 meters, filled with sand and a screened well in the center with a diameter of 0.025 m. A regulated outflow system establishes a controlled water level at the tank wall to simulate various aquifer thicknesses. The pressure head at the bottom of the tank along one axis can be measured to assess the flow profile every 0.1 m between the well and the tank wall. In order to evaluate the accuracy of the Dupuit-Thiem equation, a combination of different injection rates and aquifer thicknesses were simulated in the LSAW. Contrary to what was expected (significant differences between the measured and calculated pressure heads in the well), the absolute difference between the calculated and measured pressure head is less than 10%. Beside this, the highest differences are not observed in the well itself, but in the near proximity of it, at a radius of 0.1 m. The results further show that the difference between the calculated and measured pressure heads tends to decrease with higher flow rates. Despite its limitations (assumption of laminar and horizontal flow throughout the whole aquifer), the Dupuit-Thiem equation is considered to accurately represent the flow system in the LSAW.
Pollard, J R; Arispe, N; Rojas, E; Pollard, H B
1994-01-01
Ion channels can express multiple conductance levels that are not integer multiples of some unitary conductance, and that interconvert among one another. We report here that for 26 different types of multiple conductance channels, all allowed conductance levels can be calculated accurately using the geometric sequence gn = g(o) (3/2)n, where gn is a conductance level and n is an integer > or = 0. We refer to this relationship as the "3/2 Rule," because the value of any term in the sequence of conductances (gn) can be calculated as 3/2 times the value of the preceding term (gn-1). The experimentally determined average value for "3/2" is 1.491 +/- 0.095 (sample size = 37, average +/- SD). We also verify the choice of a 3/2 ratio on the basis of error analysis over the range of ratio values between 1.1 and 2.0. In an independent analysis using Marquardt's algorithm, we further verified the 3/2 ratio and the assignment of specific conductances to specific terms in the geometric sequence. Thus, irrespective of the open time probability, the allowed conductance levels of these channels can be described accurately to within approximately 6%. We anticipate that the "3/2 Rule" will simplify description of multiple conductance channels in a wide variety of biological systems and provide an organizing principle for channel heterogeneity and differential effects of channel blockers. PMID:7524712
BUFR2NetCDF - Converting Observational Data to a Self Describing Archive Format
NASA Astrophysics Data System (ADS)
Manross, K.; Caron, J. L.
2013-12-01
The majority of observational data collected and distributed by the World Meteorological Organization (WMO) Global Telecommunication System (GTS) are done so via the BUFR data format. There are many good reasons for this, such as the ability to store nearly any observational data type, flexibility for missing/unused parameters, and file compressibility, in other words BUFR is a very good transport container. BUFR data are a table driven data format, meaning that a separate table is maintained for the encoding/decoding of the data stored within. The WMO, as well as many other operational data centers such as the National Oceanic and Atmospheric Administration's (NOAA) National Center for Environmental Prediction (NCEP), maintain the metadata tables for storing and retrieving data within a BUFR file. Often the table data is not embedded with the BUFR files (though NCEP does embed the tables) and it can be challenging for the user to extract the table metadata, or locate the proper version of the table to obtain the needed metadata for a BUR file. More generally, non-expert users find BUFR a difficult format to parse, and to use and understand correctly. This presentation introduces a tool for converting BUFR data files to the self-describing NetCDF format. Of note is that the resulting NetCDF file will incorporate the new Discrete Sampling Geometries of the Climate and Forecast (CF) metadata convention. This will provide users of archived observational data: greater ease of use, assurance of data and metadata integrity for their research, and improved provenance.
Provenance of things - describing geochemistry observation workflows using PROV-O
NASA Astrophysics Data System (ADS)
Cox, S. J. D.; Car, N. J.
2015-12-01
Geochemistry observations typically follow a complex preparation process after sample retrieval from the field. Description of these are required to allow readers and other data users to assess the reliability of the data produced, and to ensure reproducibility. While laboratory notebooks are used for private record-keeping, and laboratory information systems (LIMS) on a facility basis, this data is not generally published, and there are no standard formats for transfer. And while there is some standardization of workflows, this is often scoped to a lab, or an instrument. New procedures and workflows are being developed continually - in fact this is a key expectation in the development of the science. Thus formalization of the description of sample preparation and observations must be both rigorous and flexible. We have been exploring the use of the W3C Provenance model (PROV) to capture complete traces, including both the real world things and the data generated. PROV has a core data model that distinguishes between entities, agents and activities involved in producing a piece of data or thing in the world. While the design of PROV was primarily conditioned by stories concerning information resources, application is not restricted to the production of digital or information assets. PROV allowing a comprehensive trace of predecessor entities and transformations at any level of detail. In this paper we demonstrate the use of PROV for describing specimens managed for scientific observations. Two examples are considered: a geological sample which undergoes a typical preparation process for measurements of the concentration of a particular chemical substance, and the collection, taxonomic classification and eventual publication of an insect specimen. PROV enables the material that goes into the instrument to be linked back to the sample retrieved in the field. This complements the IGSN system, which focuses on registration of field sample identity to support the
Kluxen, G; Hoerauf, A
2008-01-01
One of the most significant contributions to tropical medicine and ophthalmology was made by Jean Hissette: African ocular onchocerciasis. During his extensive investigations in the Babindi country, he found numerous adults with river blindness. Their eye disease was caused by the filaria Onchocerca volvulus Leuckart. He noticed the signs of interstitial keratitis and band keratopathy, faint iritis or iridocyclitis, posterior synechiae and often a downward distortion of the pupil. He was the first to describe chorioretinal scarring of the fundus, what became known as the Hissette-Ridley fundus. People reported to him their entoptic phenomena which he unequivocally interpreted to be the images of microfilariae in the patient's own eye. During his stay in Belgium in 1932, he elucidated the pathogenesis of blindness since he was able to provide histological proof of the presence of microfilariae in various ocular tissues of an enucleated eye from a patient living near the Sankuru river. Like other serious health impairments, the severe inflammatory lesions in the eye occurred only after the microfilariae had died. Hence he realized that dying microfilariae play a key role in the mechanisms leading to blindness. Hissette's precise descriptions were the logical fruit of his outstanding observational abilities and enabled him as a man of great intuition to speculate about causal relationships. He evidently benefited from the fact that he took the native Africans seriously and asked them their opinion. In 1933, his friend and teacher Dr. De Mets in Antwerp already wrote on Hissette's discovery in the Belgian Congo: "This study is of exceptional value to specialists which is not only a tribute to its author, but to our common native country (Belgium)." PMID:18546927
Carstensen, Marius; Thomsen, Claus; Hermansen, Kjeld
2003-08-01
Elevation of postprandial triacylglycerol (TG)-rich plasma lipoproteins is considered potentially atherogenic. Type 2 diabetic patients have exaggerated postprandial TG compared with healthy subjects. Postprandial TG responses to oral fat loads are usually studied as the area under the TG curve. No consensus exists regarding the method of choice when calculating the TG response area. We evaluated the correlation between fasting TG and postprandial TG responses calculated by the trapezoid rule as total area under the curve (AUC) and incremental area under the curve (iAUC). Furthermore, we compared the AUC and iAUC to a 3-point calculation method. Ten healthy subjects and 47 type 2 diabetic patients ingested test meals consisting of an energy-free soup plus 80 g fat and 50 g carbohydrate. TG responses were measured in total plasma, in a chylomicron (CM)-rich fraction and in a CM-poor fraction. In healthy subjects the AUC, but not iAUC, correlated positively to fasting TG. In type 2 diabetic patients a strong correlation was found between fasting TG and AUC, whereas weak associations were found to the iAUCs. The iAUC was strongly correlated to the postprandial TG rise in both groups. The 3-point areas differed significantly from the trapezoid measurements in both healthy and type 2 diabetic subjects. In conclusion, in both healthy and type 2 diabetic subjects total AUC is highly correlated to fasting TG, whereas iAUC more accurately describes the TG response to an oral fat load. The 3-point test seems less suitable for the determination of postprandial response in both healthy and type 2 diabetic subjects. PMID:12898469
ERIC Educational Resources Information Center
Halpin, Peter F.; Kieffer, Michael J.
2015-01-01
The authors outline the application of latent class analysis (LCA) to classroom observational instruments. LCA offers diagnostic information about teachers' instructional strengths and weaknesses, along with estimates of measurement error for individual teachers, while remaining relatively straightforward to implement and interpret. It is…
Describing the observed cosmic neutrinos by interactions of nuclei with matter
NASA Astrophysics Data System (ADS)
Winter, Walter
2014-11-01
IceCube has observed neutrinos that are presumably of extra-Galactic origin. Since specific sources have not yet been identified, we discuss what could be learned from the conceptual point of view. We use a simple model for neutrino production from the interactions between nuclei and matter, and we focus on the description of the spectral shape and flavor composition observed by IceCube. Our main parameters are the spectral index, maximal energy, magnetic field, and composition of the accelerated nuclei. We show that a cutoff at PeV energies can be achieved by soft enough spectra, a cutoff of the primary energy, or strong enough magnetic fields. These options, however, are difficult to reconcile with the hypothesis that these neutrinos originate from the same sources as the ultrahigh-energy cosmic rays. We demonstrate that heavier nuclei accelerated in the sources may be a possible way out if the maximal energy scales appropriately with the mass number of the nuclei. In this scenario, neutrino observations can actually be used to test the ultrahigh-energy cosmic ray acceleration mechanism. We also emphasize the need for a volume upgrade of the IceCube detector for future precision physics, for which the flavor information becomes a statistically meaningful model discriminator as well as a qualitatively new ingredient.
Applying an accurate spherical model to gamma-ray burst afterglow observations
NASA Astrophysics Data System (ADS)
Leventis, K.; van der Horst, A. J.; van Eerten, H. J.; Wijers, R. A. M. J.
2013-05-01
We present results of model fits to afterglow data sets of GRB 970508, GRB 980703 and GRB 070125, characterized by long and broad-band coverage. The model assumes synchrotron radiation (including self-absorption) from a spherical adiabatic blast wave and consists of analytic flux prescriptions based on numerical results. For the first time it combines the accuracy of hydrodynamic simulations through different stages of the outflow dynamics with the flexibility of simple heuristic formulas. The prescriptions are especially geared towards accurate description of the dynamical transition of the outflow from relativistic to Newtonian velocities in an arbitrary power-law density environment. We show that the spherical model can accurately describe the data only in the case of GRB 970508, for which we find a circumburst medium density n ∝ r-2. We investigate in detail the implied spectra and physical parameters of that burst. For the microphysics we show evidence for equipartition between the fraction of energy density carried by relativistic electrons and magnetic field. We also find that for the blast wave to be adiabatic, the fraction of electrons accelerated at the shock has to be smaller than 1. We present best-fitting parameters for the afterglows of all three bursts, including uncertainties in the parameters of GRB 970508, and compare the inferred values to those obtained by different authors.
Bonetto, Paola; Qi, Jinyi; Leahy, Richard M.
1999-10-01
We describe a method for computing linear observer statistics for maximum a posteriori (MAP) reconstructions of PET images. The method is based on a theoretical approximation for the mean and covariance of MAP reconstructions. In particular, we derive here a closed form for the channelized Hotelling observer (CHO) statistic applied to 2D MAP images. We show reasonably good correspondence between these theoretical results and Monte Carlo studies. The accuracy and low computational cost of the approximation allow us to analyze the observer performance over a wide range of operating conditions and parameter settings for the MAP reconstruction algorithm.
Accurate CT-MR image registration for deep brain stimulation: a multi-observer evaluation study
NASA Astrophysics Data System (ADS)
Rühaak, Jan; Derksen, Alexander; Heldmann, Stefan; Hallmann, Marc; Meine, Hans
2015-03-01
Since the first clinical interventions in the late 1980s, Deep Brain Stimulation (DBS) of the subthalamic nucleus has evolved into a very effective treatment option for patients with severe Parkinson's disease. DBS entails the implantation of an electrode that performs high frequency stimulations to a target area deep inside the brain. A very accurate placement of the electrode is a prerequisite for positive therapy outcome. The assessment of the intervention result is of central importance in DBS treatment and involves the registration of pre- and postinterventional scans. In this paper, we present an image processing pipeline for highly accurate registration of postoperative CT to preoperative MR. Our method consists of two steps: a fully automatic pre-alignment using a detection of the skull tip in the CT based on fuzzy connectedness, and an intensity-based rigid registration. The registration uses the Normalized Gradient Fields distance measure in a multilevel Gauss-Newton optimization framework and focuses on a region around the subthalamic nucleus in the MR. The accuracy of our method was extensively evaluated on 20 DBS datasets from clinical routine and compared with manual expert registrations. For each dataset, three independent registrations were available, thus allowing to relate algorithmic with expert performance. Our method achieved an average registration error of 0.95mm in the target region around the subthalamic nucleus as compared to an inter-observer variability of 1.12 mm. Together with the short registration time of about five seconds on average, our method forms a very attractive package that can be considered ready for clinical use.
NASA Astrophysics Data System (ADS)
Willis, D. M.; Stephenson, F. R.
2000-01-01
Early auroral observations recorded in various oriental histories are examined in order to search for examples of strictly simultaneous and indisputably independent observations of the aurora borealis from spatially separated sites in East Asia. In the period up to ad 1700, only five examples have been found of two or more oriental auroral observations from separate sites on the same night. These occurred during the nights of ad 1101 January 31, ad 1138 October 6, ad 1363 July 30, ad 1582 March 8 and ad 1653 March 2. The independent historical evidence describing observations of mid-latitude auroral displays at more than one site in East Asia on the same night provides virtually incontrovertible proof that auroral displays actually occurred on these five special occasions. This conclusion is corroborated by the good level of agreement between the detailed auroral descriptions recorded in the different oriental histories, which furnish essentially compatible information on both the colour (or colours) of each auroral display and its approximate position in the sky. In addition, the occurrence of auroral displays in Europe within two days of auroral displays in East Asia, on two (possibly three) out of these five special occasions, suggests that a substantial number of the mid-latitude auroral displays recorded in the oriental histories are associated with intense geomagnetic storms.
NASA Astrophysics Data System (ADS)
Joshi, Jagdish C.; Winter, Walter; Gupta, Nayantara
2014-04-01
Cosmic rays diffuse through the interstellar medium and interact with matter and radiations as long as they are trapped in the Galactic magnetic field. The IceCube experiment has detected some TeV-PeV neutrino events whose origin is yet unknown. We study if all or a fraction of these events can be described by the interactions of cosmic rays with matter. We consider the average target density needed to explain them for different halo sizes and shapes, the effect of the chemical composition of the cosmic rays, the impact of the directional information of the neutrino events, and the constraints from gamma-ray bounds and their direction. We do not require knowledge of the cosmic ray escape time or injection for our approach. We find that, given all constraints, at most 0.1 of the observed neutrino events in IceCube can be described by cosmic ray interactions with matter. In addition, we demonstrate that the currently established chemical composition of the cosmic rays contradicts a peak of the neutrino spectrum at PeV energies.
Can All Cosmological Observations Be Accurately Interpreted with a Unique Geometry?
NASA Astrophysics Data System (ADS)
Fleury, Pierre; Dupuy, Hélène; Uzan, Jean-Philippe
2013-08-01
The recent analysis of the Planck results reveals a tension between the best fits for (Ωm0, H0) derived from the cosmic microwave background or baryonic acoustic oscillations on the one hand, and the Hubble diagram on the other hand. These observations probe the Universe on very different scales since they involve light beams of very different angular sizes; hence, the tension between them may indicate that they should not be interpreted the same way. More precisely, this Letter questions the accuracy of using only the (perturbed) Friedmann-Lemaître geometry to interpret all the cosmological observations, regardless of their angular or spatial resolution. We show that using an inhomogeneous “Swiss-cheese” model to interpret the Hubble diagram allows us to reconcile the inferred value of Ωm0 with the Planck results. Such an approach does not require us to invoke new physics nor to violate the Copernican principle.
Can all cosmological observations be accurately interpreted with a unique geometry?
Fleury, Pierre; Dupuy, Hélène; Uzan, Jean-Philippe
2013-08-30
The recent analysis of the Planck results reveals a tension between the best fits for (Ω(m0), H(0)) derived from the cosmic microwave background or baryonic acoustic oscillations on the one hand, and the Hubble diagram on the other hand. These observations probe the Universe on very different scales since they involve light beams of very different angular sizes; hence, the tension between them may indicate that they should not be interpreted the same way. More precisely, this Letter questions the accuracy of using only the (perturbed) Friedmann-Lemaître geometry to interpret all the cosmological observations, regardless of their angular or spatial resolution. We show that using an inhomogeneous "Swiss-cheese" model to interpret the Hubble diagram allows us to reconcile the inferred value of Ω(m0) with the Planck results. Such an approach does not require us to invoke new physics nor to violate the Copernican principle. PMID:24033020
Accurate stellar masses for SB2 components: Interferometric observations for Gaia validation
NASA Astrophysics Data System (ADS)
Halbwachs, J.-L.; Boffin, H. M. J.; Le Bouquin, J.-B.; Famaey, B.; Salomon, J.-B.; Arenou, F.; Pourbaix, D.; Anthonioz, F.; Grellmann, R.; Guieu, S.; Guillout, P.; Jorissen, A.; Kiefer, F.; Lebreton, Y.; Mazeh, T.; Nebot Gómez-Morán, A.; Sana, H.; Tal-Or, L.
2015-12-01
A sample of about 70 double-lined spectroscopic binaries (SB2) is followed with radial velocity (RV) measurements, in order to derive the masses of their components when the astrometric measurements of Gaia will be available. A subset of 6 SB2 was observed in interferometry with VLTI/PIONIER, and the components were separated for each binary. The RV measurements already obtained were combined with the interferometric observations and the masses of the components were derived. The accuracies of the 12 masses are presently between 0.4 and 7 %, but they will still be improved in the future. These masses will be used to validate the masses which will be obtained from Gaia. In addition, the parallaxes derived from the combined visual+spectroscopic orbits are compared to that of Hipparcos, and a mass-luminosity relation is derived in the infrared H band.
Extracting Accurate and Precise Topography from Lroc Narrow Angle Camera Stereo Observations
NASA Astrophysics Data System (ADS)
Henriksen, M. R.; Manheim, M. R.; Speyerer, E. J.; Robinson, M. S.; LROC Team
2016-06-01
The Lunar Reconnaissance Orbiter Camera (LROC) includes two identical Narrow Angle Cameras (NAC) that acquire meter scale imaging. Stereo observations are acquired by imaging from two or more orbits, including at least one off-nadir slew. Digital terrain models (DTMs) generated from the stereo observations are controlled to Lunar Orbiter Laser Altimeter (LOLA) elevation profiles. With current processing methods, digital terrain models (DTM) have absolute accuracies commensurate than the uncertainties of the LOLA profiles (~10 m horizontally and ~1 m vertically) and relative horizontal and vertical precisions better than the pixel scale of the DTMs (2 to 5 m). The NAC stereo pairs and derived DTMs represent an invaluable tool for science and exploration purposes. We computed slope statistics from 81 highland and 31 mare DTMs across a range of baselines. Overlapping DTMs of single stereo sets were also combined to form larger area DTM mosaics, enabling detailed characterization of large geomorphic features and providing a key resource for future exploration planning. Currently, two percent of the lunar surface is imaged in NAC stereo and continued acquisition of stereo observations will serve to strengthen our knowledge of the Moon and geologic processes that occur on all the terrestrial planets.
Offner, Stella S. R.; Robitaille, Thomas P.; Hansen, Charles E.; Klein, Richard I.; McKee, Christopher F.
2012-07-10
The properties of unresolved protostars and their local environment are frequently inferred from spectral energy distributions (SEDs) using radiative transfer modeling. In this paper, we use synthetic observations of realistic star formation simulations to evaluate the accuracy of properties inferred from fitting model SEDs to observations. We use ORION, an adaptive mesh refinement (AMR) three-dimensional gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent molecular cloud including the effects of protostellar outflows. To obtain the dust temperature distribution and SEDs of the forming protostars, we post-process the simulations using HYPERION, a state-of-the-art Monte Carlo radiative transfer code. We find that the ORION and HYPERION dust temperatures typically agree within a factor of two. We compare synthetic SEDs of embedded protostars for a range of evolutionary times, simulation resolutions, aperture sizes, and viewing angles. We demonstrate that complex, asymmetric gas morphology leads to a variety of classifications for individual objects as a function of viewing angle. We derive best-fit source parameters for each SED through comparison with a pre-computed grid of radiative transfer models. While the SED models correctly identify the evolutionary stage of the synthetic sources as embedded protostars, we show that the disk and stellar parameters can be very discrepant from the simulated values, which is expected since the disk and central source are obscured by the protostellar envelope. Parameters such as the stellar accretion rate, stellar mass, and disk mass show better agreement, but can still deviate significantly, and the agreement may in some cases be artificially good due to the limited range of parameters in the set of model SEDs. Lack of correlation between the model and simulation properties in many individual instances cautions against overinterpreting properties inferred from SEDs for unresolved protostellar
Luo, Xiongbiao; Wan, Ying; He, Xiangjian; Mori, Kensaku
2015-08-01
This paper proposes an observation-driven adaptive differential evolution algorithm that fuses bronchoscopic video sequences, electromagnetic sensor measurements, and computed tomography images for accurate and smooth bronchoscope three-dimensional motion tracking. Currently an electromagnetic tracker with a position sensor fixed at the bronchoscope tip is commonly used to estimate bronchoscope movements. The large tracking error from directly using sensor measurements, which may be deteriorated heavily by patient respiratory motion and the magnetic field distortion of the tracker, limits clinical applications. How to effectively use sensor measurements for precise and stable bronchoscope electromagnetic tracking remains challenging. We here exploit an observation-driven adaptive differential evolution framework to address such a challenge and boost the tracking accuracy and smoothness. In our framework, two advantageous points are distinguished from other adaptive differential evolution methods: (1) the current observation including sensor measurements and bronchoscopic video images is used in the mutation equation and the fitness computation, respectively and (2) the mutation factor and the crossover rate are determined adaptively on the basis of the current image observation. The experimental results demonstrate that our framework provides much more accurate and smooth bronchoscope tracking than the state-of-the-art methods. Our approach reduces the tracking error from 3.96 to 2.89 mm, improves the tracking smoothness from 4.08 to 1.62 mm, and increases the visual quality from 0.707 to 0.741. PMID:25660001
Henneges, Carsten; Reed, Catherine; Chen, Yun-Fei; Dell’Agnello, Grazia; Lebrec, Jeremie
2016-01-01
Background: Improved understanding of the pattern of cognitive decline in Alzheimer’s disease (AD) would be useful to assist primary care physicians in explaining AD progression to patients and caregivers. Objective: To identify the sequence in which cognitive abilities decline in community-dwelling patients with AD. Methods: Baseline data were analyzed from 1,495 patients diagnosed with probable AD and a Mini-Mental State Examination (MMSE) score ≤ 26 enrolled in the 18-month observational GERAS study. Proportional odds logistic regression models were applied to model MMSE subscores (orientation, registration, attention and concentration, recall, language, and drawing) and the corresponding subscores of the cognitive subscale of the Alzheimer’s Disease Assessment Scale (ADAS-cog), using MMSE total score as the index of disease progression. Probabilities of impairment start and full impairment were estimated at each MMSE total score level. Results: From the estimated probabilities for each MMSE subscore as a function of the MMSE total score, the first aspect of cognition to start being impaired was recall, followed by orientation in time, attention and concentration, orientation in place, language, drawing, and registration. For full impairment in subscores, the sequence was recall, drawing, attention and concentration, orientation in time, orientation in place, registration, and language. The sequence of cognitive decline for the corresponding ADAS-cog subscores was remarkably consistent with this pattern. Conclusion: The sequence of cognitive decline in AD can be visualized in an animation using probability estimates for key aspects of cognition. This might be useful for clinicians to set expectations on disease progression for patients and caregivers. PMID:27079700
NASA Astrophysics Data System (ADS)
Gritsyk, P. A.; Somov, B. V.
2016-08-01
The M7.7 solar flare of July 19, 2012, at 05:58 UT was observed with high spatial, temporal, and spectral resolutions in the hard X-ray and optical ranges. The flare occurred at the solar limb, which allowed us to see the relative positions of the coronal and chromospheric X-ray sources and to determine their spectra. To explain the observations of the coronal source and the chromospheric one unocculted by the solar limb, we apply an accurate analytical model for the kinetic behavior of accelerated electrons in a flare. We interpret the chromospheric hard X-ray source in the thick-target approximation with a reverse current and the coronal one in the thin-target approximation. Our estimates of the slopes of the hard X-ray spectra for both sources are consistent with the observations. However, the calculated intensity of the coronal source is lower than the observed one by several times. Allowance for the acceleration of fast electrons in a collapsing magnetic trap has enabled us to remove this contradiction. As a result of our modeling, we have estimated the flux density of the energy transferred by electrons with energies above 15 keV to be ˜5 × 1010 erg cm-2 s-1, which exceeds the values typical of the thick-target model without a reverse current by a factor of ˜5. To independently test the model, we have calculated the microwave spectrum in the range 1-50 GHz that corresponds to the available radio observations.
NASA Astrophysics Data System (ADS)
Zaksek, K.; Pick, L.; Lombardo, V.; Hort, M. K.
2015-12-01
Measuring the heat emission from active volcanic features on the basis of infrared satellite images contributes to the volcano's hazard assessment. Because these thermal anomalies only occupy a small fraction (< 1 %) of a typically resolved target pixel (e.g. from Landsat 7, MODIS) the accurate determination of the hotspot's size and temperature is however problematic. Conventionally this is overcome by comparing observations in at least two separate infrared spectral wavebands (Dual-Band method). We investigate the resolution limits of this thermal un-mixing technique by means of a uniquely designed indoor analog experiment. Therein the volcanic feature is simulated by an electrical heating alloy of 0.5 mm diameter installed on a plywood panel of high emissivity. Two thermographic cameras (VarioCam high resolution and ImageIR 8300 by Infratec) record images of the artificial heat source in wavebands comparable to those available from satellite data. These range from the short-wave infrared (1.4-3 µm) over the mid-wave infrared (3-8 µm) to the thermal infrared (8-15 µm). In the conducted experiment the pixel fraction of the hotspot was successively reduced by increasing the camera-to-target distance from 3 m to 35 m. On the basis of an individual target pixel the expected decrease of the hotspot pixel area with distance at a relatively constant wire temperature of around 600 °C was confirmed. The deviation of the hotspot's pixel fraction yielded by the Dual-Band method from the theoretically calculated one was found to be within 20 % up until a target distance of 25 m. This means that a reliable estimation of the hotspot size is only possible if the hotspot is larger than about 3 % of the pixel area, a resolution boundary most remotely sensed volcanic hotspots fall below. Future efforts will focus on the investigation of a resolution limit for the hotspot's temperature by varying the alloy's amperage. Moreover, the un-mixing results for more realistic multi
Silva, S M; Clozato, C L; Moraes-Barros, N; Morgante, J S
2013-08-01
The common three-toed sloth is a widespread species, but the location and the observation of its individuals are greatly hindered by its biological features. Their camouflaged pelage, its slow and quiet movements, and the strictly arboreal habits resulted in the publication of sparse, fragmented and not patterned information on the common sloth behaviour. Thus, herein we propose an updated standardized behavioural categories' framework to the study of the species. Furthermore we describe two never reported interaction behaviours: a probable mating / courtship ritual between male and female; and apparent recognition behaviour between two males. Finally we highlight the contribution of small-duration field works in this elusive species ethological study. PMID:24212693
Sengupta, Manajit; Clothiaux, Eugene E.; Ackerman, Thomas P.; Kato, Seiji; Min, Qilong
2003-09-15
A one-year observational study of overcast boundary layer stratus at the U.S. Department of Energy Atmospheric Radiation Measurement Program Southern Great Plains site illustrates that surface radiation is primarily sensitive to cloud liquid water path, with cloud drop effective radius having a secondary influence. The mean, median and standard deviation of cloud liquid water path and cloud drop effective radius for the dataset are 0.120 mm, 0.101 mm, 0.108 mm, and 7.38 {micro}m, 7.13 {micro}m, 2.39 {micro}m, respectively. Radiative transfer calculations demonstrate that cloud optical depth and cloud normalized forcing are respectively three and six times as sensitive to liquid water path variations as they are to effective radius variations, when the observed ranges of each of those variables is considered. Overall, there is a 79% correlation between observed and computed surface fluxes when using a fixed effective radius of 7.5 {micro}m and observed liquid water paths in the calculations. One conclusion from this study is that measurement of the indirect aerosol effect will be problematic at the site, as variations in cloud liquid water path will most likely mask effects of variations in particle size.
NASA Technical Reports Server (NTRS)
Turco, R. P.; Hamill, P.; Toon, O. B.; Whitten, R. C.; Kiang, C. S.
1979-01-01
A new time-dependent one-dimensional model of the stratospheric sulfate aerosol layer is developed. The model treats atmospheric photochemistry and aerosol physics in detail and includes the interaction between gases and particles explicitly. It is shown that the numerical algorithms used in the model are quite precise. Sensitivity studies and comparison with observations are made. The simulated aerosol physics generates a particle layer with most of the observed properties. The sensitivity of the calculated properties to changes in a large number of aeronomic aerosol parameters is discussed in some detail. The sensitivity analysis reveals areas where the aerosol model is most uncertain. New observations are suggested that might help resolve important questions about the origin of the stratospheric aerosol layer.
Barone, Vincenzo; Biczysko, Malgorzata; Bloino, Julien; Cimino, Paola; Penocchio, Emanuele; Puzzarini, Cristina
2015-09-01
The structures and relative stabilities as well as the rotational and vibrational spectra of the three low-energy conformers of pyruvic acid (PA) have been characterized using a state-of-the-art quantum-mechanical approach designed for flexible molecules. By making use of the available experimental rotational constants for several isotopologues of the most stable PA conformer, Tc-PA, the semiexperimental equilibrium structure has been derived. The latter provides a reference for the pure theoretical determination of the equilibrium geometries for all conformers, thus confirming for these structures an accuracy of 0.001 Å and 0.1 deg for bond lengths and angles, respectively. Highly accurate relative energies of all conformers (Tc-, Tt-, and Ct-PA) and of the transition states connecting them are provided along with the thermodynamic properties at low and high temperatures, thus leading to conformational enthalpies accurate to 1 kJ mol(-1). Concerning microwave spectroscopy, rotational constants accurate to about 20 MHz are provided for the Tt- and Ct-PA conformers, together with the computed centrifugal-distortion constants and dipole moments required to simulate their rotational spectra. For Ct-PA, vibrational frequencies in the mid-infrared region accurate to 10 cm(-1) are reported along with theoretical estimates for the transitions in the near-infrared range, and the corresponding infrared spectrum including fundamental transitions, overtones, and combination bands has been simulated. In addition to the new data described above, theoretical results for the Tc- and Tt-PA conformers are compared with all available experimental data to further confirm the accuracy of the hybrid coupled-cluster/density functional theory (CC/DFT) protocol applied in the present study. Finally, we discuss in detail the accuracy of computational models fully based on double-hybrid DFT functionals (mainly at the B2PLYP/aug-cc-pVTZ level) that avoid the use of very expensive CC
Learning to Describe, Describing to Understand
ERIC Educational Resources Information Center
Knoester, Matthew
2008-01-01
In this essay, the author describes his understanding and experience with descriptive review processes, as developed by Patricia Carini (Himley 2000) and members of the Prospect Center in North Bennington, VT. The author critically reviews the benefits and limitations of using descriptive review as a form of assessment of students, teaching…
Hasnain, Sabeeha; McClendon, Christopher L; Hsu, Monica T; Jacobson, Matthew P; Bandyopadhyay, Pradipta
2014-01-01
A new coarse-grained model of the E. coli cytoplasm is developed by describing the proteins of the cytoplasm as flexible units consisting of one or more spheres that follow Brownian dynamics (BD), with hydrodynamic interactions (HI) accounted for by a mean-field approach. Extensive BD simulations were performed to calculate the diffusion coefficients of three different proteins in the cellular environment. The results are in close agreement with experimental or previously simulated values, where available. Control simulations without HI showed that use of HI is essential to obtain accurate diffusion coefficients. Anomalous diffusion inside the crowded cellular medium was investigated with Fractional Brownian motion analysis, and found to be present in this model. By running a series of control simulations in which various forces were removed systematically, it was found that repulsive interactions (volume exclusion) are the main cause for anomalous diffusion, with a secondary contribution from HI. PMID:25180859
NASA Technical Reports Server (NTRS)
Sandford, Stephen P.
2010-01-01
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is one of four Tier 1 missions recommended by the recent NRC Decadal Survey report on Earth Science and Applications from Space (NRC, 2007). The CLARREO mission addresses the need to provide accurate, broadly acknowledged climate records that are used to enable validated long-term climate projections that become the foundation for informed decisions on mitigation and adaptation policies that address the effects of climate change on society. The CLARREO mission accomplishes this critical objective through rigorous SI traceable decadal change observations that are sensitive to many of the key uncertainties in climate radiative forcings, responses, and feedbacks that in turn drive uncertainty in current climate model projections. These same uncertainties also lead to uncertainty in attribution of climate change to anthropogenic forcing. For the first time CLARREO will make highly accurate, global, SI-traceable decadal change observations sensitive to the most critical, but least understood, climate forcings, responses, and feedbacks. The CLARREO breakthrough is to achieve the required levels of accuracy and traceability to SI standards for a set of observations sensitive to a wide range of key decadal change variables. The required accuracy levels are determined so that climate trend signals can be detected against a background of naturally occurring variability. Climate system natural variability therefore determines what level of accuracy is overkill, and what level is critical to obtain. In this sense, the CLARREO mission requirements are considered optimal from a science value perspective. The accuracy for decadal change traceability to SI standards includes uncertainties associated with instrument calibration, satellite orbit sampling, and analysis methods. Unlike most space missions, the CLARREO requirements are driven not by the instantaneous accuracy of the measurements, but by accuracy in
NASA Astrophysics Data System (ADS)
Negrón-Juárez, Robinson I.; Koven, Charles D.; Riley, William J.; Knox, Ryan G.; Chambers, Jeffrey Q.
2015-06-01
A significant fraction of anthropogenic CO2 emissions is assimilated by tropical forests and stored as biomass, slowing the accumulation of CO2 in the atmosphere. Because different plant tissues have different functional roles and turnover times, predictions of carbon balance of tropical forests depend on how earth system models (ESMs) represent the dynamic allocation of productivity to different tree compartments. This study shows that observed allocation of productivity, biomass, and turnover times of main tree compartments (leaves, wood, and roots) are not accurately represented in Coupled Model Intercomparison Project Phase 5 ESMs. In particular, observations indicate that biomass saturates with increasing productivity. In contrast, most models predict continuous increases in biomass with increases in productivity. This bias may lead to an over-prediction of carbon uptake in response to CO2 or climate-driven changes in productivity. Compartment-specific productivity and biomass are useful benchmarks to assess terrestrial ecosystem model performance. Improvements in the predicted allocation patterns and turnover times by ESMs will reduce uncertainties in climate predictions.
Describing Cognitive Structure.
ERIC Educational Resources Information Center
White, Richard T.
This paper discusses questions pertinent to a definition of cognitive structure as the knowledge one possesses and the manner in which it is arranged, and considers how to select or devise methods of describing cognitive structure. The main purpose in describing cognitive structure is to see whether differences in memory (or cognitive structure)…
Describe Your Favorite Teacher.
ERIC Educational Resources Information Center
Dill, Isaac; Dill, Vicky
1993-01-01
A third grader describes Ms. Gonzalez, his favorite teacher, who left to accept a more lucrative teaching assignment. Ms. Gonzalez' butterflies unit covered everything from songs about social butterflies to paintings of butterfly wings, anatomy studies, and student haiku poems and biographies. Students studied biology by growing popcorn plants…
New described dermatological disorders.
Gönül, Müzeyyen; Cevirgen Cemil, Bengu; Keseroglu, Havva Ozge; Kaya Akis, Havva
2014-01-01
Many advances in dermatology have been made in recent years. In the present review article, newly described disorders from the last six years are presented in detail. We divided these reports into different sections, including syndromes, autoinflammatory diseases, tumors, and unclassified disease. Syndromes included are "circumferential skin creases Kunze type" and "unusual type of pachyonychia congenita or a new syndrome"; autoinflammatory diseases include "chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome," "pyoderma gangrenosum, acne, and hidradenitis suppurativa (PASH) syndrome," and "pyogenic arthritis, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PAPASH) syndrome"; tumors include "acquired reactive digital fibroma," "onychocytic matricoma and onychocytic carcinoma," "infundibulocystic nail bed squamous cell carcinoma," and "acral histiocytic nodules"; unclassified disorders include "saurian papulosis," "symmetrical acrokeratoderma," "confetti-like macular atrophy," and "skin spicules," "erythema papulosa semicircularis recidivans." PMID:25243162
New Described Dermatological Disorders
Cevirgen Cemil, Bengu; Keseroglu, Havva Ozge; Kaya Akis, Havva
2014-01-01
Many advances in dermatology have been made in recent years. In the present review article, newly described disorders from the last six years are presented in detail. We divided these reports into different sections, including syndromes, autoinflammatory diseases, tumors, and unclassified disease. Syndromes included are “circumferential skin creases Kunze type” and “unusual type of pachyonychia congenita or a new syndrome”; autoinflammatory diseases include “chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome,” “pyoderma gangrenosum, acne, and hidradenitis suppurativa (PASH) syndrome,” and “pyogenic arthritis, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PAPASH) syndrome”; tumors include “acquired reactive digital fibroma,” “onychocytic matricoma and onychocytic carcinoma,” “infundibulocystic nail bed squamous cell carcinoma,” and “acral histiocytic nodules”; unclassified disorders include “saurian papulosis,” “symmetrical acrokeratoderma,” “confetti-like macular atrophy,” and “skin spicules,” “erythema papulosa semicircularis recidivans.” PMID:25243162
Using Neural Networks to Describe Tracer Correlations
NASA Technical Reports Server (NTRS)
Lary, D. J.; Mueller, M. D.; Mussa, H. Y.
2003-01-01
Neural networks are ideally suited to describe the spatial and temporal dependence of tracer-tracer correlations. The neural network performs well even in regions where the correlations are less compact and normally a family of correlation curves would be required. For example, the CH4-N2O correlation can be well described using a neural network trained with the latitude, pressure, time of year, and CH4 volume mixing ratio (v.m.r.). In this study a neural network using Quickprop learning and one hidden layer with eight nodes was able to reproduce the CH4-N2O correlation with a correlation co- efficient of 0.9995. Such an accurate representation of tracer-tracer correlations allows more use to be made of long-term datasets to constrain chemical models. Such as the dataset from the Halogen Occultation Experiment (HALOE) which has continuously observed CH4, (but not N2O) from 1991 till the present. The neural network Fortran code used is available for download.
NASA Astrophysics Data System (ADS)
Zhu, Baoyou; Ma, Ming; Xu, Weiwei; Ma, Dong
2015-12-01
Properties of negative cloud-to-ground (CG) lightning flashes, in terms of number of strokes per flash, inter-stroke intervals and the relative intensity of subsequent and first strokes, were presented by accurate-stroke-count studies based on all 1085 negative flashes from a local thunderstorm. The percentage of single-stroke flashes and stroke multiplicity evolved significantly during the whole life cycle of the study thunderstorm. The occurrence probability of negative CG flashes decreased exponentially with the increasing number of strokes per flash. About 30.5% of negative CG flashes contained only one stroke and number of strokes per flash averaged 3.3. In a subset of 753 negative multiple-stroke flashes, about 41.4% contained at least one subsequent stroke stronger than the corresponding first stroke. Subsequent strokes tended to decrease in strength with their orders and the ratio of subsequent to first stroke peaks presented a geometric mean value of 0.52. Interestingly, negative CG flashes of higher multiplicity tended to have stronger initial strokes. 2525 inter-stroke intervals showed a more or less log-normal distribution and gave a geometric mean value of 62 ms. For CG flashes of particular multiplicity geometric mean inter-stroke intervals tended to decrease with the increasing number of strokes per flash, while those intervals associated with higher order strokes tended to be larger than those associated with low order strokes.
NASA Astrophysics Data System (ADS)
Kiefer, F.; Halbwachs, J.-L.; Arenou, F.; Pourbaix, D.; Famaey, B.; Guillout, P.; Lebreton, Y.; Nebot Gómez-Morán, A.; Mazeh, T.; Salomon, J.-B.; Soubiran, C.; Tal-Or, L.
2016-05-01
In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the Spectrographe pour l'Observation des PHénomènes des Intérieurs Stellaires et des Exoplanètes spectrograph at the Haute-Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1 per cent when the astrometric measurements of Gaia are taken into account. In this paper, we present the results from five years of observations of 10 SB2 systems with periods ranging from 37 to 881 d. Using the TODMOR algorithm, we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the components are then obtained with an accuracy better than 1.2 per cent for the 10 binaries. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 87895 with an accuracy of 0.98 and 1.2 per cent, respectively.
Accurate quantum chemical calculations
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.
1989-01-01
An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.
NASA Astrophysics Data System (ADS)
Schneider, Matthias; Wiegele, Andreas; Barthlott, Sabine; González, Yenny; Christner, Emanuel; Dyroff, Christoph; García, Omaira E.; Hase, Frank; Blumenstock, Thomas; Sepúlveda, Eliezer; Mengistu Tsidu, Gizaw; Takele Kenea, Samuel; Rodríguez, Sergio; Andrey, Javier
2016-07-01
In the lower/middle troposphere, {H2O,δD} pairs are good proxies for moisture pathways; however, their observation, in particular when using remote sensing techniques, is challenging. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) addresses this challenge by integrating the remote sensing with in situ measurement techniques. The aim is to retrieve calibrated tropospheric {H2O,δD} pairs from the middle infrared spectra measured from ground by FTIR (Fourier transform infrared) spectrometers of the NDACC (Network for the Detection of Atmospheric Composition Change) and the thermal nadir spectra measured by IASI (Infrared Atmospheric Sounding Interferometer) aboard the MetOp satellites. In this paper, we present the final MUSICA products, and discuss the characteristics and potential of the NDACC/FTIR and MetOp/IASI {H2O,δD} data pairs. First, we briefly resume the particularities of an {H2O,δD} pair retrieval. Second, we show that the remote sensing data of the final product version are absolutely calibrated with respect to H2O and δD in situ profile references measured in the subtropics, between 0 and 7 km. Third, we reveal that the {H2O,δD} pair distributions obtained from the different remote sensors are consistent and allow distinct lower/middle tropospheric moisture pathways to be identified in agreement with multi-year in situ references. Fourth, we document the possibilities of the NDACC/FTIR instruments for climatological studies (due to long-term monitoring) and of the MetOp/IASI sensors for observing diurnal signals on a quasi-global scale and with high horizontal resolution. Fifth, we discuss the risk of misinterpreting {H2O,δD} pair distributions due to incomplete processing of the remote sensing products.
Model describes subsea control dynamics
Not Available
1988-02-01
A mathematical model of the hydraulic control systems for subsea completions and their umbilicals has been developed and applied successfully to Jabiru and Challis field production projects in the Timor Sea. The model overcomes the limitations of conventional linear steady state models and yields for the hydraulic system an accurate description of its dynamic response, including the valve shut-in times and the pressure transients. Results of numerical simulations based on the model are in good agreement with measurements of the dynamic response of the tree valves and umbilicals made during land testing.
Roessler, Erich; Vélez, Jorge I.; Zhou, Nan; Muenke, Maximilian
2012-01-01
Clinical molecular diagnostic centers routinely screen SHH, ZIC2, SIX3 and TGIF for mutations that can help to explain holoprosencephaly and related brain malformations. Here we report a prospective Sanger sequence analysis of 189 unrelated probands referred to our diagnostic lab for genetic testing. We identified 28 novel unique mutations in this group (15%) and no instances of deleterious mutations in two genes in the same subject. Our result extends that of other diagnostic centers and suggests that among the aggregate 475 prospectively sequenced holoprosencephaly probands there is negligible evidence for direct gene-gene interactions among these tested genes. We model the predictions of the observed mutation frequency in the context of the hypothesis that gene x gene interactions are a prerequisite for forebrain malformations, i.e. the “multiple-hit” hypothesis. We conclude that such a direct interaction would be expected to be rare and that more subtle genetic and environmental interactions are a better explanation for the clinically observed inter- and intra-familial variability. PMID:22310223
Heuijerjans, Ashley; Matikainen, Marko K.; Julkunen, Petro; Eliasson, Pernilla; Aspenberg, Per; Isaksson, Hanna
2015-01-01
Background Computational models of Achilles tendons can help understanding how healthy tendons are affected by repetitive loading and how the different tissue constituents contribute to the tendon’s biomechanical response. However, available models of Achilles tendon are limited in their description of the hierarchical multi-structural composition of the tissue. This study hypothesised that a poroviscoelastic fibre-reinforced model, previously successful in capturing cartilage biomechanical behaviour, can depict the biomechanical behaviour of the rat Achilles tendon found experimentally. Materials and Methods We developed a new material model of the Achilles tendon, which considers the tendon’s main constituents namely: water, proteoglycan matrix and collagen fibres. A hyperelastic formulation of the proteoglycan matrix enabled computations of large deformations of the tendon, and collagen fibres were modelled as viscoelastic. Specimen-specific finite element models were created of 9 rat Achilles tendons from an animal experiment and simulations were carried out following a repetitive tensile loading protocol. The material model parameters were calibrated against data from the rats by minimising the root mean squared error (RMS) between experimental force data and model output. Results and Conclusions All specimen models were successfully fitted to experimental data with high accuracy (RMS 0.42-1.02). Additional simulations predicted more compliant and soft tendon behaviour at reduced strain-rates compared to higher strain-rates that produce a stiff and brittle tendon response. Stress-relaxation simulations exhibited strain-dependent stress-relaxation behaviour where larger strains produced slower relaxation rates compared to smaller strain levels. Our simulations showed that the collagen fibres in the Achilles tendon are the main load-bearing component during tensile loading, where the orientation of the collagen fibres plays an important role for the tendon’s viscoelastic response. In conclusion, this model can capture the repetitive loading and unloading behaviour of intact and healthy Achilles tendons, which is a critical first step towards understanding tendon homeostasis and function as this biomechanical response changes in diseased tendons. PMID:26030436
How accurately can the microcanonical ensemble describe small isolated quantum systems?
NASA Astrophysics Data System (ADS)
Ikeda, Tatsuhiko N.; Ueda, Masahito
2015-08-01
We numerically investigate quantum quenches of a nonintegrable hard-core Bose-Hubbard model to test the accuracy of the microcanonical ensemble in small isolated quantum systems. We show that, in a certain range of system size, the accuracy increases with the dimension of the Hilbert space D as 1 /D . We ascribe this rapid improvement to the absence of correlations between many-body energy eigenstates. Outside of that range, the accuracy is found to scale either as 1 /√{D } or algebraically with the system size.
Technology Transfer Automated Retrieval System (TEKTRAN)
The ability of ecosystems to sequester carbon (C) is largely dependent on how global changes in climate will alter the balance between rates of decomposition and net primary production. The response of primary production to changes in climate has been examined using reasonably well-validated mechan...
Describing Control in Educational Organizations.
ERIC Educational Resources Information Center
Renihan, P. J.; Renihan, F. I.
This paper describes the construction and application of a framework to investigate control at the policy-making level in education. The minutes of the regular meetings of 21 school boards in British Columbia were analyzed for the period January to December of 1975. Construction of the framework involved (1) definitions of control and…
How to describe disordered structures
NASA Astrophysics Data System (ADS)
Nishio, Kengo; Miyazaki, Takehide
2016-04-01
Disordered structures such as liquids and glasses, grains and foams, galaxies, etc. are often represented as polyhedral tilings. Characterizing the associated polyhedral tiling is a promising strategy to understand the disordered structure. However, since a variety of polyhedra are arranged in complex ways, it is challenging to describe what polyhedra are tiled in what way. Here, to solve this problem, we create the theory of how the polyhedra are tiled. We first formulate an algorithm to convert a polyhedron into a codeword that instructs how to construct the polyhedron from its building-block polygons. By generalizing the method to polyhedral tilings, we describe the arrangements of polyhedra. Our theory allows us to characterize polyhedral tilings, and thereby paves the way to study from short- to long-range order of disordered structures in a systematic way.
How to describe disordered structures.
Nishio, Kengo; Miyazaki, Takehide
2016-01-01
Disordered structures such as liquids and glasses, grains and foams, galaxies, etc. are often represented as polyhedral tilings. Characterizing the associated polyhedral tiling is a promising strategy to understand the disordered structure. However, since a variety of polyhedra are arranged in complex ways, it is challenging to describe what polyhedra are tiled in what way. Here, to solve this problem, we create the theory of how the polyhedra are tiled. We first formulate an algorithm to convert a polyhedron into a codeword that instructs how to construct the polyhedron from its building-block polygons. By generalizing the method to polyhedral tilings, we describe the arrangements of polyhedra. Our theory allows us to characterize polyhedral tilings, and thereby paves the way to study from short- to long-range order of disordered structures in a systematic way. PMID:27064833
How to describe disordered structures
Nishio, Kengo; Miyazaki, Takehide
2016-01-01
Disordered structures such as liquids and glasses, grains and foams, galaxies, etc. are often represented as polyhedral tilings. Characterizing the associated polyhedral tiling is a promising strategy to understand the disordered structure. However, since a variety of polyhedra are arranged in complex ways, it is challenging to describe what polyhedra are tiled in what way. Here, to solve this problem, we create the theory of how the polyhedra are tiled. We first formulate an algorithm to convert a polyhedron into a codeword that instructs how to construct the polyhedron from its building-block polygons. By generalizing the method to polyhedral tilings, we describe the arrangements of polyhedra. Our theory allows us to characterize polyhedral tilings, and thereby paves the way to study from short- to long-range order of disordered structures in a systematic way. PMID:27064833
Describing Young Children's Deductive Reasoning.
ERIC Educational Resources Information Center
Reid, David A.
This paper reports results related to the development of a consistent descriptive language for research on mathematical reasoning. Ways of reasoning deductively are highlighted, using examples drawn from observations of young students. One-step deductions versus multi-step deductions, known versus hypothetical premises, and single versus multiple…
ERIC Educational Resources Information Center
Rom, Mark Carl
2011-01-01
Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…
Large robotized turning centers described
NASA Astrophysics Data System (ADS)
Kirsanov, V. V.; Tsarenko, V. I.
1985-09-01
The introduction of numerical control (NC) machine tools has made it possible to automate machining in series and small series production. The organization of automated production sections merged NC machine tools with automated transport systems. However, both the one and the other require the presence of an operative at the machine for low skilled operations. Industrial robots perform a number of auxiliary operations, such as equipment loading-unloading and control, changing cutting and auxiliary tools, controlling workpieces and parts, and cleaning of location surfaces. When used with a group of equipment they perform transfer operations between the machine tools. Industrial robots eliminate the need for workers to form auxiliary operations. This underscores the importance of developing robotized manufacturing centers providing for minimal human participation in production and creating conditions for two and three shift operation of equipment. Work carried out at several robotized manufacturing centers for series and small series production is described.
Five Describing Factors of Dyslexia.
Tamboer, Peter; Vorst, Harrie C M; Oort, Frans J
2016-09-01
Two subtypes of dyslexia (phonological, visual) have been under debate in various studies. However, the number of symptoms of dyslexia described in the literature exceeds the number of subtypes, and underlying relations remain unclear. We investigated underlying cognitive features of dyslexia with exploratory and confirmatory factor analyses. A sample of 446 students (63 with dyslexia) completed a large test battery and a large questionnaire. Five factors were found in both the test battery and the questionnaire. These 10 factors loaded on 5 latent factors (spelling, phonology, short-term memory, rhyme/confusion, and whole-word processing/complexity), which explained 60% of total variance. Three analyses supported the validity of these factors. A confirmatory factor analysis fit with a solution of five factors (RMSEA = .03). Those with dyslexia differed from those without dyslexia on all factors. A combination of five factors provided reliable predictions of dyslexia and nondyslexia (accuracy >90%). We also looked for factorial deficits on an individual level to construct subtypes of dyslexia, but found varying profiles. We concluded that a multiple cognitive deficit model of dyslexia is supported, whereas the existence of subtypes remains unclear. We discussed the results in relation to advanced compensation strategies of students, measures of intelligence, and various correlations within groups of those with and without dyslexia. PMID:25398549
Accurate monotone cubic interpolation
NASA Technical Reports Server (NTRS)
Huynh, Hung T.
1991-01-01
Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.
Accurate Finite Difference Algorithms
NASA Technical Reports Server (NTRS)
Goodrich, John W.
1996-01-01
Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.
Quantum formalism to describe binocular rivalry.
Manousakis, Efstratios
2009-11-01
On the basis of the general character and operation of the process of perception, a formalism is sought to mathematically describe the subjective or abstract/mental process of perception. It is shown that the formalism of orthodox quantum theory of measurement, where the observer plays a key role, is a broader mathematical foundation which can be adopted to describe the dynamics of the subjective experience. The mathematical formalism describes the psychophysical dynamics of the subjective or cognitive experience as communicated to us by the subject. Subsequently, the formalism is used to describe simple perception processes and, in particular, to describe the probability distribution of dominance duration obtained from the testimony of subjects experiencing binocular rivalry. Using this theory and parameters based on known values of neuronal oscillation frequencies and firing rates, the calculated probability distribution of dominance duration of rival states in binocular rivalry under various conditions is found to be in good agreement with available experimental data. This theory naturally explains an observed marked increase in dominance duration in binocular rivalry upon periodic interruption of stimulus and yields testable predictions for the distribution of perceptual alteration in time. PMID:19520143
NASA Astrophysics Data System (ADS)
Itano, Wayne M.; Ramsey, Norman F.
1993-07-01
The paper discusses current methods for accurate measurements of time by conventional atomic clocks, with particular attention given to the principles of operation of atomic-beam frequency standards, atomic hydrogen masers, and atomic fountain and to the potential use of strings of trapped mercury ions as a time device more stable than conventional atomic clocks. The areas of application of the ultraprecise and ultrastable time-measuring devices that tax the capacity of modern atomic clocks include radio astronomy and tests of relativity. The paper also discusses practical applications of ultraprecise clocks, such as navigation of space vehicles and pinpointing the exact position of ships and other objects on earth using the GPS.
CRITICAL ELEMENTS IN DESCRIBING AND UNDERSTANDING OUR NATION'S AQUATIC RESOURCES
Despite spending $115 billion per year on environmental actions in the United States, we have only a limited ability to describe the effectiveness of these expenditures. Moreover, after decades of such investments, we cannot accurately describe status and trends in the nation's a...
Describing Ecosystem Complexity through Integrated Catchment Modeling
NASA Astrophysics Data System (ADS)
Shope, C. L.; Tenhunen, J. D.; Peiffer, S.
2011-12-01
Land use and climate change have been implicated in reduced ecosystem services (ie: high quality water yield, biodiversity, and agricultural yield. The prediction of ecosystem services expected under future land use decisions and changing climate conditions has become increasingly important. Complex policy and management decisions require the integration of physical, economic, and social data over several scales to assess effects on water resources and ecology. Field-based meteorology, hydrology, soil physics, plant production, solute and sediment transport, economic, and social behavior data were measured in a South Korean catchment. A variety of models are being used to simulate plot and field scale experiments within the catchment. Results from each of the local-scale models provide identification of sensitive, local-scale parameters which are then used as inputs into a large-scale watershed model. We used the spatially distributed SWAT model to synthesize the experimental field data throughout the catchment. The approach of our study was that the range in local-scale model parameter results can be used to define the sensitivity and uncertainty in the large-scale watershed model. Further, this example shows how research can be structured for scientific results describing complex ecosystems and landscapes where cross-disciplinary linkages benefit the end result. The field-based and modeling framework described is being used to develop scenarios to examine spatial and temporal changes in land use practices and climatic effects on water quantity, water quality, and sediment transport. Development of accurate modeling scenarios requires understanding the social relationship between individual and policy driven land management practices and the value of sustainable resources to all shareholders.
[Who really first described lesser blood circulation?].
Masić, Izet; Dilić, Mirza
2007-01-01
Today, at least 740 years since professor and director of the Al Mansouri Hospital in Cairo Ibn al-Nafis (1210-1288), in his paper about pulse described small (pulmonary) blood circulatory system. At the most popular web search engines very often we can find its name, especially in English language. Majority of quotes about Ibn Nefis are on Arabic or Turkish language, although Ibn Nefis discovery is of world wide importance. Author Masić I. (1993) is among rare ones who in some of the indexed journals emphasized of that event, and on that debated also some authors from Great Britain and USA in the respectable magazine Annals of Internal Medicine. Citations in majority mentioning other two "describers" or "discoverers" of pulmonary blood circulation, Michael Servetus (1511-1553), physician and theologist, and William Harvey (1578-1657), which in his paper "Exercitatio anatomica de motu cordis et sanguinis in animalibus" published in 1628 described blood circulatory system. Ibn Nefis is due to its scientific work called "Second Avicenna". Some of his papers, during centuries were translated into Latin, and some published as a reprint in Arabic language. Professor Fuat Sezgin from Frankfurt published a compendium of Ibn Nefis papers in 1997. Also, Masić I. (1997) has published one monography about Ibn Nefis. Importance of Ibn Nefis epochal discovery is the fact that it is solely based on deductive impressions, because his description of the small circulation is not occurred by observation on corps during section. It is known that he did not pay attention to the Galen's theories about blood circulation. His prophecy sentence say: "If I don't know that my work will not last up to ten thousand years after me, I would not write them". Sapient sat. PMID:21553447
Accurate and occlusion-robust multi-view stereo
NASA Astrophysics Data System (ADS)
Zhu, Zhaokun; Stamatopoulos, Christos; Fraser, Clive S.
2015-11-01
This paper proposes an accurate multi-view stereo method for image-based 3D reconstruction that features robustness in the presence of occlusions. The new method offers improvements in dealing with two fundamental image matching problems. The first concerns the selection of the support window model, while the second centers upon accurate visibility estimation for each pixel. The support window model is based on an approximate 3D support plane described by a depth and two per-pixel depth offsets. For the visibility estimation, the multi-view constraint is initially relaxed by generating separate support plane maps for each support image using a modified PatchMatch algorithm. Then the most likely visible support image, which represents the minimum visibility of each pixel, is extracted via a discrete Markov Random Field model and it is further augmented by parameter clustering. Once the visibility is estimated, multi-view optimization taking into account all redundant observations is conducted to achieve optimal accuracy in the 3D surface generation for both depth and surface normal estimates. Finally, multi-view consistency is utilized to eliminate any remaining observational outliers. The proposed method is experimentally evaluated using well-known Middlebury datasets, and results obtained demonstrate that it is amongst the most accurate of the methods thus far reported via the Middlebury MVS website. Moreover, the new method exhibits a high completeness rate.
NNLOPS accurate associated HW production
NASA Astrophysics Data System (ADS)
Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia
2016-06-01
We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.
How to accurately bypass damage
Broyde, Suse; Patel, Dinshaw J.
2016-01-01
Ultraviolet radiation can cause cancer through DNA damage — specifically, by linking adjacent thymine bases. Crystal structures show how the enzyme DNA polymerase η accurately bypasses such lesions, offering protection. PMID:20577203
Describing functions for nonlinear optical systems.
Ghosh, A K
1997-10-10
The concept of describing functions is useful for analyzing and designing nonlinear systems. A proposal for using the idea of describing functions for studying the behavior of a nonlinear optical processing system is given. The describing function can be used in the same way that a coherent transfer function or optical transfer function is used to characterize linear, shift-invariant optical processors. Two coherent optical systems for measuring the magnitude of the describing function of nonlinear optical processors are suggested. PMID:18264243
Accurate Evaluation of Quantum Integrals
NASA Technical Reports Server (NTRS)
Galant, David C.; Goorvitch, D.
1994-01-01
Combining an appropriate finite difference method with Richardson's extrapolation results in a simple, highly accurate numerical method for solving a Schr\\"{o}dinger's equation. Important results are that error estimates are provided, and that one can extrapolate expectation values rather than the wavefunctions to obtain highly accurate expectation values. We discuss the eigenvalues, the error growth in repeated Richardson's extrapolation, and show that the expectation values calculated on a crude mesh can be extrapolated to obtain expectation values of high accuracy.
An accurate registration technique for distorted images
NASA Technical Reports Server (NTRS)
Delapena, Michele; Shaw, Richard A.; Linde, Peter; Dravins, Dainis
1990-01-01
Accurate registration of International Ultraviolet Explorer (IUE) images is crucial because the variability of the geometrical distortions that are introduced by the SEC-Vidicon cameras ensures that raw science images are never perfectly aligned with the Intensity Transfer Functions (ITFs) (i.e., graded floodlamp exposures that are used to linearize and normalize the camera response). A technique for precisely registering IUE images which uses a cross correlation of the fixed pattern that exists in all raw IUE images is described.
Cellular automata to describe seismicity: A review
NASA Astrophysics Data System (ADS)
Jiménez, Abigail
2013-12-01
Cellular Automata have been used in the literature to describe seismicity. We first historically introduce Cellular Automata and provide some important definitions. Then we proceed to review the most important models, most of them being variations of the spring-block model proposed by Burridge and Knopoff, and describe the most important results obtained from them. We discuss the relation with criticality and also describe some models that try to reproduce real data.
Kostylev, Maxim; Wilson, David
2014-01-01
Lignocellulosic biomass is a potential source of renewable, low-carbon-footprint liquid fuels. Biomass recalcitrance and enzyme cost are key challenges associated with the large-scale production of cellulosic fuel. Kinetic modeling of enzymatic cellulose digestion has been complicated by the heterogeneous nature of the substrate and by the fact that a true steady state cannot be attained. We present a two-parameter kinetic model based on the Michaelis-Menten scheme (Michaelis L and Menten ML. (1913) Biochem Z 49:333–369), but with a time-dependent activity coefficient analogous to fractal-like kinetics formulated by Kopelman (Kopelman R. (1988) Science 241:1620–1626). We provide a mathematical derivation and experimental support to show that one of the parameters is a total activity coefficient and the other is an intrinsic constant that reflects the ability of the cellulases to overcome substrate recalcitrance. The model is applicable to individual cellulases and their mixtures at low-to-medium enzyme loads. Using biomass degrading enzymes from a cellulolytic bacterium Thermobifida fusca we show that the model can be used for mechanistic studies of enzymatic cellulose digestion. We also demonstrate that it applies to the crude supernatant of the widely studied cellulolytic fungus Trichoderma reesei and can thus be used to compare cellulases from different organisms. The two parameters may serve a similar role to Vmax, KM, and kcat in classical kinetics. A similar approach may be applicable to other enzymes with heterogeneous substrates and where a steady state is not achievable. PMID:23837567
Venus general atmosphere circulation described by Pioneer
NASA Technical Reports Server (NTRS)
1981-01-01
The predominant weather pattern for Venus is described. Wind directions and wind velocities are given. Possible driving forces of the winds are presented and include solar heating, planetary rotation, and the greenhouse effect.
78 FR 34604 - Submitting Complete and Accurate Information
Federal Register 2010, 2011, 2012, 2013, 2014
2013-06-10
... COMMISSION 10 CFR Part 50 Submitting Complete and Accurate Information AGENCY: Nuclear Regulatory Commission... accurate information as would a licensee or an applicant for a license.'' DATES: Submit comments by August... may submit comments by any of the following methods (unless this document describes a different...
Describing content in middle school science curricula
NASA Astrophysics Data System (ADS)
Schwarz-Ballard, Jennifer A.
As researchers and designers, we intuitively recognize differences between curricula and describe them in terms of design strategy: project-based, laboratory-based, modular, traditional, and textbook, among others. We assume that practitioners recognize the differences in how each requires that students use knowledge, however these intuitive differences have not been captured or systematically described by the existing languages for describing learning goals. In this dissertation I argue that we need new ways of capturing relationships among elements of content, and propose a theory that describes some of the important differences in how students reason in differently designed curricula and activities. Educational researchers and curriculum designers have taken a variety of approaches to laying out learning goals for science. Through an analysis of existing descriptions of learning goals I argue that to describe differences in the understanding students come away with, they need to (1) be specific about the form of knowledge, (2) incorporate both the processes through which knowledge is used and its form, and (3) capture content development across a curriculum. To show the value of inquiry curricula, learning goals need to incorporate distinctions among the variety of ways we ask students to use knowledge. Here I propose the Epistemic Structures Framework as one way to describe differences in students reasoning that are not captured by existing descriptions of learning goals. The usefulness of the Epistemic Structures framework is demonstrated in the four curriculum case study examples in Part II of this work. The curricula in the case studies represent a range of content coverage, curriculum structure, and design rationale. They serve both to illustrate the Epistemic Structures analysis process and make the case that it does in fact describe learning goals in a way that captures important differences in students reasoning in differently designed curricula
Audio-Described Educational Materials: Ugandan Teachers' Experiences
ERIC Educational Resources Information Center
Wormnaes, Siri; Sellaeg, Nina
2013-01-01
This article describes and discusses a qualitative, descriptive, and exploratory study of how 12 visually impaired teachers in Uganda experienced audio-described educational video material for teachers and student teachers. The study is based upon interviews with these teachers and observations while they were using the material either…
Sensorimotor Interference When Reasoning About Described Environments
NASA Astrophysics Data System (ADS)
Avraamides, Marios N.; Kyranidou, Melina-Nicole
The influence of sensorimotor interference was examined in two experiments that compared pointing with iconic arrows and verbal responding in a task that entailed locating target-objects from imagined perspectives. Participants studied text narratives describing objects at locations around them in a remote environment and then responded to targets from memory. Results revealed only minor differences between the two response modes suggesting that bodily cues do not exert severe detrimental interference on spatial reasoning from imagined perspective when non-immediate described environments are used. The implications of the findings are discussed.
Recently described neoplasms of the sinonasal tract.
Bishop, Justin A
2016-03-01
Surgical pathology of the sinonasal region (i.e., nasal cavity and the paranasal sinuses) is notoriously difficult, due in part to the remarkable diversity of neoplasms that may be encountered in this area. In addition, a number of neoplasms have been only recently described in the sinonasal tract, further compounding the difficulty for pathologists who are not yet familiar with them. This manuscript will review the clinicopathologic features of some of the recently described sinonasal tumor types: NUT midline carcinoma, HPV-related carcinoma with adenoid cystic-like features, SMARCB1 (INI-1) deficient sinonasal carcinoma, biphenotypic sinonasal sarcoma, and adamantinoma-like Ewing family tumor. PMID:26776744
USING TRACERS TO DESCRIBE NAPL HETEROGENEITY
Tracers are frequently used to estimate both the average travel time for water flow through the tracer swept volume and NAPL saturation. The same data can be used to develop a statistical distribution describing the hydraulic conductivity in the sept volume and a possible distri...
Describing Technological Paradigm Transitions: A Methodological Exploration.
ERIC Educational Resources Information Center
Wallace, Danny P.; Van Fleet, Connie
1997-01-01
Presents a humorous treatment of the "sessio taurino" (or humanistic inquiry) technique for describing changes in technological models. The fundamental tool of "sessio taurino" is a loosely-structured event known as the session, which is of indeterminate length, involves a flexible number of participants, and utilizes a preundetermined set of…
Is the Water Heating Curve as Described?
ERIC Educational Resources Information Center
Riveros, H. G.; Oliva, A. I.
2008-01-01
We analysed the heating curve of water which is described in textbooks. An experiment combined with some simple heat transfer calculations is discussed. The theoretical behaviour can be altered by changing the conditions under which the experiment is modelled. By identifying and controlling the different parameters involved during the heating…
How Digital Native Learners Describe Themselves
ERIC Educational Resources Information Center
Thompson, Penny
2015-01-01
Eight university students from the "digital native" generation were interviewed about the connections they saw between technology use and learning, and also their reactions to the popular press claims about their generation. Themes that emerged from the interviews were coded to show patterns in how digital natives describe themselves.…
CANDLE syndrome: a recently described autoinflammatory syndrome.
Tüfekçi, Özlem; Bengoa, ŞebnemYilmaz; Karapinar, Tuba Hilkay; Ataseven, Eda Büke; İrken, Gülersu; Ören, Hale
2015-05-01
CANDLE syndrome (chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature) is a recently described autoinflammatory syndrome characterized by early onset, recurrent fever, skin lesions, and multisystemic inflammatory manifestations. Most of the patients have been shown to have mutation in PSMB8 gene. Herein, we report a 2-year-old patient with young onset recurrent fever, atypical facies, widespread skin lesions, generalized lymphadenopathy, hepatosplenomegaly, joint contractures, hypertrglyceridemia, lipodystrophy, and autoimmune hemolytic anemia. Clinical features together with the skin biopsy findings were consistent with the CANDLE syndrome. The pathogenesis and treatment of this syndrome have not been fully understood. Increased awareness of this recently described syndrome may lead to recognition of new cases and better understanding of its pathogenesis which in turn may help for development of an effective treatment. PMID:25036278
Accurate Weather Forecasting for Radio Astronomy
NASA Astrophysics Data System (ADS)
Maddalena, Ronald J.
2010-01-01
The NRAO Green Bank Telescope routinely observes at wavelengths from 3 mm to 1 m. As with all mm-wave telescopes, observing conditions depend upon the variable atmospheric water content. The site provides over 100 days/yr when opacities are low enough for good observing at 3 mm, but winds on the open-air structure reduce the time suitable for 3-mm observing where pointing is critical. Thus, to maximum productivity the observing wavelength needs to match weather conditions. For 6 years the telescope has used a dynamic scheduling system (recently upgraded; www.gb.nrao.edu/DSS) that requires accurate multi-day forecasts for winds and opacities. Since opacity forecasts are not provided by the National Weather Services (NWS), I have developed an automated system that takes available forecasts, derives forecasted opacities, and deploys the results on the web in user-friendly graphical overviews (www.gb.nrao.edu/ rmaddale/Weather). The system relies on the "North American Mesoscale" models, which are updated by the NWS every 6 hrs, have a 12 km horizontal resolution, 1 hr temporal resolution, run to 84 hrs, and have 60 vertical layers that extend to 20 km. Each forecast consists of a time series of ground conditions, cloud coverage, etc, and, most importantly, temperature, pressure, humidity as a function of height. I use the Liebe's MWP model (Radio Science, 20, 1069, 1985) to determine the absorption in each layer for each hour for 30 observing wavelengths. Radiative transfer provides, for each hour and wavelength, the total opacity and the radio brightness of the atmosphere, which contributes substantially at some wavelengths to Tsys and the observational noise. Comparisons of measured and forecasted Tsys at 22.2 and 44 GHz imply that the forecasted opacities are good to about 0.01 Nepers, which is sufficient for forecasting and accurate calibration. Reliability is high out to 2 days and degrades slowly for longer-range forecasts.
LiveDescribe: Can Amateur Describers Create High-Quality Audio Description?
ERIC Educational Resources Information Center
Branje, Carmen J.; Fels, Deborah I.
2012-01-01
Introduction: The study presented here evaluated the usability of the audio description software LiveDescribe and explored the acceptance rates of audio description created by amateur describers who used LiveDescribe to facilitate the creation of their descriptions. Methods: Twelve amateur describers with little or no previous experience with…
A Method for Describing Preschoolers' Activity Preferences
ERIC Educational Resources Information Center
Hanley, Gregory P.; Cammilleri, Anthony P.; Tiger, Jeffrey H.; Ingvarsson, Einar T.
2007-01-01
We designed a series of analyses to develop a measurement system capable of simultaneously recording the free-play patterns of 20 children in a preschool classroom. Study 1 determined the intermittency with which the location and engagement of each child could be momentarily observed before the accuracy of the measurement was compromised. Results…
Is an eclipse described in the Odyssey?
Baikouzis, Constantino; Magnasco, Marcelo O.
2008-01-01
Plutarch and Heraclitus believed a certain passage in the 20th book of the Odyssey (“Theoclymenus's prophecy”) to be a poetic description of a total solar eclipse. In the late 1920s, Schoch and Neugebauer computed that the solar eclipse of 16 April 1178 B.C.E. was total over the Ionian Islands and was the only suitable eclipse in more than a century to agree with classical estimates of the decade-earlier sack of Troy around 1192–1184 B.C.E. However, much skepticism remains about whether the verses refer to this, or any, eclipse. To contribute to the issue independently of the disputed eclipse reference, we analyze other astronomical references in the Epic, without assuming the existence of an eclipse, and search for dates matching the astronomical phenomena we believe they describe. We use three overt astronomical references in the epic: to Boötes and the Pleiades, Venus, and the New Moon; we supplement them with a conjectural identification of Hermes's trip to Ogygia as relating to the motion of planet Mercury. Performing an exhaustive search of all possible dates in the span 1250–1115 B.C., we looked to match these phenomena in the order and manner that the text describes. In that period, a single date closely matches our references: 16 April 1178 B.C.E. We speculate that these references, plus the disputed eclipse reference, may refer to that specific eclipse. PMID:18577587
Is an eclipse described in the Odyssey?
Baikouzis, Constantino; Magnasco, Marcelo O
2008-07-01
Plutarch and Heraclitus believed a certain passage in the 20th book of the Odyssey ("Theoclymenus's prophecy") to be a poetic description of a total solar eclipse. In the late 1920s, Schoch and Neugebauer computed that the solar eclipse of 16 April 1178 B.C.E. was total over the Ionian Islands and was the only suitable eclipse in more than a century to agree with classical estimates of the decade-earlier sack of Troy around 1192-1184 B.C.E. However, much skepticism remains about whether the verses refer to this, or any, eclipse. To contribute to the issue independently of the disputed eclipse reference, we analyze other astronomical references in the Epic, without assuming the existence of an eclipse, and search for dates matching the astronomical phenomena we believe they describe. We use three overt astronomical references in the epic: to Boötes and the Pleiades, Venus, and the New Moon; we supplement them with a conjectural identification of Hermes's trip to Ogygia as relating to the motion of planet Mercury. Performing an exhaustive search of all possible dates in the span 1250-1115 B.C., we looked to match these phenomena in the order and manner that the text describes. In that period, a single date closely matches our references: 16 April 1178 B.C.E. We speculate that these references, plus the disputed eclipse reference, may refer to that specific eclipse. PMID:18577587
Describing Story Evolution from Dynamic Information Streams
Rose, Stuart J.; Butner, R. Scott; Cowley, Wendy E.; Gregory, Michelle L.; Walker, Julia
2009-10-12
Sources of streaming information, such as news syndicates, publish information continuously. Information portals and news aggregators list the latest information from around the world enabling information consumers to easily identify events in the past 24 hours. The volume and velocity of these streams causes information from prior days’ to quickly vanish despite its utility in providing an informative context for interpreting new information. Few capabilities exist to support an individual attempting to identify or understand trends and changes from streaming information over time. The burden of retaining prior information and integrating with the new is left to the skills, determination, and discipline of each individual. In this paper we present a visual analytics system for linking essential content from information streams over time into dynamic stories that develop and change over multiple days. We describe particular challenges to the analysis of streaming information and explore visual representations for showing story change and evolution over time.
Does Guru Granth Sahib describe depression?
Kalra, Gurvinder; Bhui, Kamaldeep; Bhugra, Dinesh
2013-01-01
Sikhism is a relatively young religion, with Guru Granth Sahib as its key religious text. This text describes emotions in everyday life, such as happiness, sadness, anger, hatred, and also more serious mental health issues such as depression and psychosis. There are references to the causation of these emotional disturbances and also ways to get out of them. We studied both the Gurumukhi version and the English translation of the Guru Granth Sahib to understand what it had to say about depression, its henomenology, and religious prescriptions for recovery. We discuss these descriptions in this paper and understand its meaning within the context of clinical depression. Such knowledge is important as explicit descriptions about depression and sadness can help encourage culturally appropriate assessment and treatment, as well as promote public health through education. PMID:23858254
Stimulated recall interviews for describing pragmatic epistemology
NASA Astrophysics Data System (ADS)
Shubert, Christopher W.; Meredith, Dawn C.
2015-12-01
Students' epistemologies affect how and what they learn: do they believe physics is a list of equations, or a coherent and sensible description of the physical world? In order to study these epistemologies as part of curricular assessment, we adopt the resources framework, which posits that students have many productive epistemological resources that can be brought to bear as they learn physics. In previous studies, these epistemologies have been either inferred from behavior in learning contexts or probed through surveys or interviews outside of the learning context. We argue that stimulated recall interviews provide a contextually and interpretively valid method to access students' epistemologies that complement existing methods. We develop a stimulated recall interview methodology to assess a curricular intervention and find evidence that epistemological resources aptly describe student epistemologies.
Simplified stock markets described by number operators
NASA Astrophysics Data System (ADS)
Bagarello, F.
2009-06-01
In this paper we continue our systematic analysis of the operatorial approach previously proposed in an economical context and we discuss a mixed toy model of a simplified stock market, i.e. a model in which the price of the shares is given as an input. We deduce the time evolution of the portfolio of the various traders of the market, as well as of other observable quantities. As in a previous paper, we solve the equations of motion by means of a fixed point like approximation.
Thermodynamic model to describe miscibility in complex fluid systems
Guerrero, M.I.
1982-01-01
In the basic studies of tertiary oil recovery, it is necessary to describe the phase diagrams of mixtures of hydrocarbons, surfactants and brine. It has been observed that certain features of those phase diagrams, such as the appearance of 3-phase regions, can be correlated to ultra-low interfacial tensions. In this work, a simple thermodynamic model is described. The phase diagram obtained is qualitatively identical to that of real, more complex systems. 13 references.
Describing the chemical character of a magma
NASA Astrophysics Data System (ADS)
Duley, Soma; Vigneresse, Jean-Louis; Chattaraj, Pratim K.
2010-05-01
We introduce the concepts of hard-soft acid-base (HSAB) and derive parameters to characterize a magma that consists either of a solid rock, a melt or its exsolved gaseous phase. Those parameters are the electronegativity, hardness, electrophilicity, polarisability and optical basicity. They determine the chemical reactivity of each component individually, or its equivalence in the case of a complex system of elements or oxides. This results from equalization methods or from direct computation through density functional theory (DFT). Those global parameters help in characterizing magma, provide insights into the reactivity of the melt or its fluid phase when in contact with another magma, or when considering the affinity of each component for metals. In particular, the description leads to a better understanding on the mechanisms that control metal segregation and transportation during igneous activity. The trends observed during magma evolution, whether they follow a mafic or a felsic trend are also observed using these parameters and can be interpreted as approaching a greater stability. Nevertheless, the trend for felsic magma occurs at constant electrophilicity toward a silica pole of great hardness. Conversely, mafic magmas evolve at a constant hardness and decreasing electrophilicity
Predict amine solution properties accurately
Cheng, S.; Meisen, A.; Chakma, A.
1996-02-01
Improved process design begins with using accurate physical property data. Especially in the preliminary design stage, physical property data such as density viscosity, thermal conductivity and specific heat can affect the overall performance of absorbers, heat exchangers, reboilers and pump. These properties can also influence temperature profiles in heat transfer equipment and thus control or affect the rate of amine breakdown. Aqueous-amine solution physical property data are available in graphical form. However, it is not convenient to use with computer-based calculations. Developed equations allow improved correlations of derived physical property estimates with published data. Expressions are given which can be used to estimate physical properties of methyldiethanolamine (MDEA), monoethanolamine (MEA) and diglycolamine (DGA) solutions.
Accurate thickness measurement of graphene
NASA Astrophysics Data System (ADS)
Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.
2016-03-01
Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.
Plans should abstractly describe intended behavior
Pfleger, K.; Hayes-Roth, B.
1996-12-31
Planning is the process of formulating a potential course of action. How courses of action (plans) produced by a planning module are represented and how they are used by execution-oriented modules of a complex agent to influence or dictate behavior are critical architectural issues. In contrast to the traditional model of plans as executable programs that dictate precise behaviors, we claim that autonomous agents inhabiting dynamic, unpredictable environments can make better use of plans that only abstractly describe their intended behavior. Such plans only influence or constrain behavior, rather than dictating it. This idea has been discussed in a variety of contexts, but it is seldom incorporated into working complex agents. Experiments involving instantiations of our Adaptive Intelligent Systems architecture in a variety of domains have demonstrated the generality and usefulness of the approach, even with our currently simple plan representation and mechanisms for plan following. The behavioral benefits include (1) robust improvisation of goal-directed behavior in response to dynamic situations, (2) ready exploitation of dynamically acquired knowledge or behavioral capabilities, and (3) adaptation based on dynamic aspects of coordinating diverse behaviors to achieve multiple goals. In addition to these run-time advantages, the approach has useful implications for the design and configuration of agents. Indeed, the core ideas of the approach are natural extensions of fundamental ideas in software engineering.
Canada issues booklet describing acid rain
NASA Astrophysics Data System (ADS)
A booklet recently released by Environment Canada describes acid rain in terms easily understood by the general public. Although Acid Rain — The Facts tends somewhat to give the Canadian side of this intercountry controversial subject, it nevertheless presents some very interesting, simple statistics of interest to people in either the U.S. or Canada. Copies of the booklet can be obtained from Inquiry Environment Canada, Ottawa, Ontario K1A OH3, Canada, tel. 613-997-2800.The booklet points out that acid rain is caused by emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx). Once released into the atmosphere, these substances can be carried long distances by prevailing winds and return to Earth as acidic rain, snow, fog, or dust. The main sources of SO2 emissions in North America are coal-fired power generating stations and nonferrous ore smelters. The main sources of NOx emissions are vehicles and fuel combustion. From economical and environmental viewpoints, Canada believes acid rain is one of the most serious problems presently facing the country: increasing the acidity of more than 20% of Canada's 300,000 lakes to the point that aquatic life is depleted and acidity of soil water and shallow groundwater is increasing, causing decline in forest growth and water fowl populations, and eating away at buildings and monuments. Acid rain is endangering fisheries, tourism, agriculture, and forest resources in an area of 2.6 million km2 (one million square miles) of eastern Canada, about 8% of Canada's gross national product.
Using Metaphorical Models for Describing Glaciers
NASA Astrophysics Data System (ADS)
Felzmann, Dirk
2014-11-01
To date, there has only been little conceptual change research regarding conceptions about glaciers. This study used the theoretical background of embodied cognition to reconstruct different metaphorical concepts with respect to the structure of a glacier. Applying the Model of Educational Reconstruction, the conceptions of students and scientists regarding glaciers were analysed. Students' conceptions were the result of teaching experiments whereby students received instruction about glaciers and ice ages and were then interviewed about their understandings. Scientists' conceptions were based on analyses of textbooks. Accordingly, four conceptual metaphors regarding the concept of a glacier were reconstructed: a glacier is a body of ice; a glacier is a container; a glacier is a reflexive body and a glacier is a flow. Students and scientists differ with respect to in which context they apply each conceptual metaphor. It was observed, however, that students vacillate among the various conceptual metaphors as they solve tasks. While the subject context of the task activates a specific conceptual metaphor, within the discussion about the solution, the students were able to adapt their conception by changing the conceptual metaphor. Educational strategies for teaching students about glaciers require specific language to activate the appropriate conceptual metaphors and explicit reflection regarding the various conceptual metaphors.
Accurate upwind methods for the Euler equations
NASA Technical Reports Server (NTRS)
Huynh, Hung T.
1993-01-01
A new class of piecewise linear methods for the numerical solution of the one-dimensional Euler equations of gas dynamics is presented. These methods are uniformly second-order accurate, and can be considered as extensions of Godunov's scheme. With an appropriate definition of monotonicity preservation for the case of linear convection, it can be shown that they preserve monotonicity. Similar to Van Leer's MUSCL scheme, they consist of two key steps: a reconstruction step followed by an upwind step. For the reconstruction step, a monotonicity constraint that preserves uniform second-order accuracy is introduced. Computational efficiency is enhanced by devising a criterion that detects the 'smooth' part of the data where the constraint is redundant. The concept and coding of the constraint are simplified by the use of the median function. A slope steepening technique, which has no effect at smooth regions and can resolve a contact discontinuity in four cells, is described. As for the upwind step, existing and new methods are applied in a manner slightly different from those in the literature. These methods are derived by approximating the Euler equations via linearization and diagonalization. At a 'smooth' interface, Harten, Lax, and Van Leer's one intermediate state model is employed. A modification for this model that can resolve contact discontinuities is presented. Near a discontinuity, either this modified model or a more accurate one, namely, Roe's flux-difference splitting. is used. The current presentation of Roe's method, via the conceptually simple flux-vector splitting, not only establishes a connection between the two splittings, but also leads to an admissibility correction with no conditional statement, and an efficient approximation to Osher's approximate Riemann solver. These reconstruction and upwind steps result in schemes that are uniformly second-order accurate and economical at smooth regions, and yield high resolution at discontinuities.
ERIC Educational Resources Information Center
Saudargas, Richard A.; Lentz, Frances E., Jr.
1986-01-01
Using development of a State Event Observation System as an example, the decision rules and procedures for the constructing of standardized multiple behavior observational systems that provide accurate, reliable data for school-based assessment, intervention, and research are described. Reliability and validity data from the SECOS are provided.…
Accurate ab Initio Spin Densities
2012-01-01
We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as a basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys.2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CASCI-type wave function provides insight into chemically interesting features of the molecule under study such as the distribution of α and β electrons in terms of Slater determinants, CI coefficients, and natural orbitals. The methodology is applied to an iron nitrosyl complex which we have identified as a challenging system for standard approaches [J. Chem. Theory Comput.2011, 7, 2740]. PMID:22707921
Accurate wavelength calibration method for flat-field grating spectrometers.
Du, Xuewei; Li, Chaoyang; Xu, Zhe; Wang, Qiuping
2011-09-01
A portable spectrometer prototype is built to study wavelength calibration for flat-field grating spectrometers. An accurate calibration method called parameter fitting is presented. Both optical and structural parameters of the spectrometer are included in the wavelength calibration model, which accurately describes the relationship between wavelength and pixel position. Along with higher calibration accuracy, the proposed calibration method can provide information about errors in the installation of the optical components, which will be helpful for spectrometer alignment. PMID:21929865
Describing dengue epidemics: Insights from simple mechanistic models
NASA Astrophysics Data System (ADS)
Aguiar, Maíra; Stollenwerk, Nico; Kooi, Bob W.
2012-09-01
We present a set of nested models to be applied to dengue fever epidemiology. We perform a qualitative study in order to show how much complexity we really need to add into epidemiological models to be able to describe the fluctuations observed in empirical dengue hemorrhagic fever incidence data offering a promising perspective on inference of parameter values from dengue case notifications.
Fast and accurate propagation of coherent light
Lewis, R. D.; Beylkin, G.; Monzón, L.
2013-01-01
We describe a fast algorithm to propagate, for any user-specified accuracy, a time-harmonic electromagnetic field between two parallel planes separated by a linear, isotropic and homogeneous medium. The analytical formulation of this problem (ca 1897) requires the evaluation of the so-called Rayleigh–Sommerfeld integral. If the distance between the planes is small, this integral can be accurately evaluated in the Fourier domain; if the distance is very large, it can be accurately approximated by asymptotic methods. In the large intermediate region of practical interest, where the oscillatory Rayleigh–Sommerfeld kernel must be applied directly, current numerical methods can be highly inaccurate without indicating this fact to the user. In our approach, for any user-specified accuracy ϵ>0, we approximate the kernel by a short sum of Gaussians with complex-valued exponents, and then efficiently apply the result to the input data using the unequally spaced fast Fourier transform. The resulting algorithm has computational complexity , where we evaluate the solution on an N×N grid of output points given an M×M grid of input samples. Our algorithm maintains its accuracy throughout the computational domain. PMID:24204184
The remarkable ability of turbulence model equations to describe transition
NASA Technical Reports Server (NTRS)
Wilcox, David C.
1992-01-01
This paper demonstrates how well the k-omega turbulence model describes the nonlinear growth of flow instabilities from laminar flow into the turbulent flow regime. Viscous modifications are proposed for the k-omega model that yield close agreement with measurements and with Direct Numerical Simulation results for channel and pipe flow. These modifications permit prediction of subtle sublayer details such as maximum dissipation at the surface, k approximately y(exp 2) as y approaches 0, and the sharp peak value of k near the surface. With two transition specific closure coefficients, the model equations accurately predict transition for an incompressible flat-plate boundary layer. The analysis also shows why the k-epsilon model is so difficult to use for predicting transition.
Nomenclature proposal to describe vocal fold motion impairment.
Rosen, Clark A; Mau, Ted; Remacle, Marc; Hess, Markus; Eckel, Hans E; Young, VyVy N; Hantzakos, Anastasios; Yung, Katherine C; Dikkers, Frederik G
2016-08-01
The terms used to describe vocal fold motion impairment are confusing and not standardized. This results in a failure to communicate accurately and to major limitations of interpreting research studies involving vocal fold impairment. We propose standard nomenclature for reporting vocal fold impairment. Overarching terms of vocal fold immobility and hypomobility are rigorously defined. This includes assessment techniques and inclusion and exclusion criteria for determining vocal fold immobility and hypomobility. In addition, criteria for use of the following terms have been outlined in detail: vocal fold paralysis, vocal fold paresis, vocal fold immobility/hypomobility associated with mechanical impairment of the crico-arytenoid joint and vocal fold immobility/hypomobility related to laryngeal malignant disease. This represents the first rigorously defined vocal fold motion impairment nomenclature system. This provides detailed definitions to the terms vocal fold paralysis and vocal fold paresis. PMID:26036851
Accurate Telescope Mount Positioning with MEMS Accelerometers
NASA Astrophysics Data System (ADS)
Mészáros, L.; Jaskó, A.; Pál, A.; Csépány, G.
2014-08-01
This paper describes the advantages and challenges of applying microelectromechanical accelerometer systems (MEMS accelerometers) in order to attain precise, accurate, and stateless positioning of telescope mounts. This provides a completely independent method from other forms of electronic, optical, mechanical or magnetic feedback or real-time astrometry. Our goal is to reach the subarcminute range which is considerably smaller than the field-of-view of conventional imaging telescope systems. Here we present how this subarcminute accuracy can be achieved with very cheap MEMS sensors and we also detail how our procedures can be extended in order to attain even finer measurements. In addition, our paper discusses how can a complete system design be implemented in order to be a part of a telescope control system.
Accurately Mapping M31's Microlensing Population
NASA Astrophysics Data System (ADS)
Crotts, Arlin
2004-07-01
We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity
TURTLE IN SPACE DESCRIBES NEW HUBBLE IMAGE
NASA Technical Reports Server (NTRS)
2002-01-01
NASA's Hubble Space Telescope has shown us that the shrouds of gas surrounding dying, sunlike stars (called planetary nebulae) come in a variety of strange shapes, from an 'hourglass' to a 'butterfly' to a 'stingray.' With this image of NGC 6210, the Hubble telescope has added another bizarre form to the rogues' gallery of planetary nebulae: a turtle swallowing a seashell. Giving this dying star such a weird name is less of a challenge than trying to figure out how dying stars create these unusual shapes. The larger image shows the entire nebula; the inset picture captures the complicated structure surrounding the dying star. The remarkable features of this nebula are the numerous holes in the inner shells with jets of material streaming from them. These jets produce column-shaped features that are mirrored in the opposite direction. The multiple shells of material ejected by the dying star give this planetary nebula its odd form. In the 'full nebula' image, the brighter central region looks like a 'nautilus shell'; the fainter outer structure (colored red) a 'tortoise.' The dying star is the white dot in the center. Both pictures are composite images based on observations taken Aug. 6, 1997 with the telescope's Wide Field and Planetary Camera 2. Material flung off by this central star is streaming out of holes it punched in the nautilus shell. At least four jets of material can be seen in the 'full nebula' image: a pair near 6 and 12 o'clock and another near 2 and 8 o'clock. In each pair, the jets are directly opposite each other, exemplifying their 'bipolar' nature. The jets are thought to be driven by a 'fast wind' - material propelled by radiation from the hot central star. In the inner 'nautilus' shell, bright rims outline the escape holes created by this 'wind,' such as the one at 2 o'clock. This same 'wind' appears to give rise to the prominent outer jet in the same direction. The hole in the inner shell acts like a hose nozzle, directing the flow of
TURTLE IN SPACE DESCRIBES NEW HUBBLE IMAGE
NASA Technical Reports Server (NTRS)
2002-01-01
NASA's Hubble Space Telescope has shown us that the shrouds of gas surrounding dying, sunlike stars (called planetary nebulae) come in a variety of strange shapes, from an 'hourglass' to a 'butterfly' to a 'stingray.' With this image of NGC 6210, the Hubble telescope has added another bizarre form to the rogues' gallery of planetary nebulae: a turtle swallowing a seashell. Giving this dying star such a weird name is less of a challenge than trying to figure out how dying stars create these unusual shapes. The larger image shows the entire nebula; the inset picture captures the complicated structure surrounding the dying star. The remarkable features of this nebula are the numerous holes in the inner shells with jets of material streaming from them. These jets produce column-shaped features that are mirrored in the opposite direction. The multiple shells of material ejected by the dying star give this planetary nebula its odd form. In the 'full nebula' image, the brighter central region looks like a 'nautilus shell'; the fainter outer structure (colored red) a 'tortoise.' The dying star is the white dot in the center. Both pictures are composite images based on observations taken Aug. 6, 1997 with the telescope's Wide Field and Planetary Camera 2. Material flung off by this central star is streaming out of holes it punched in the nautilus shell. At least four jets of material can be seen in the 'full nebula' image: a pair near 6 and 12 o'clock and another near 2 and 8 o'clock. In each pair, the jets are directly opposite each other, exemplifying their 'bipolar' nature. The jets are thought to be driven by a 'fast wind' - material propelled by radiation from the hot central star. In the inner 'nautilus' shell, bright rims outline the escape holes created by this 'wind,' such as the one at 2 o'clock. This same 'wind' appears to give rise to the prominent outer jet in the same direction. The hole in the inner shell acts like a hose nozzle, directing the flow of
Spatial-filter models to describe IC lithographic behavior
NASA Astrophysics Data System (ADS)
Stirniman, John P.; Rieger, Michael L.
1997-07-01
Proximity correction systems require an accurate, fast way to predict how a pattern configuration will transfer to the wafer. In this paper we present an efficient method for modeling the pattern transfer process based on Dennis Gabor's `theory of communication'. This method is based on a `convolution form' where any 2D transfer process can be modeled with a set of linear, 2D spatial filters, even when the transfer process is non-linear. We will show that this form is a general case from which other well-known process simulation models can be derived. Furthermore, we will demonstrate that the convolution form can be used to model observed phenomena, even when the physical mechanisms involved are unknown.
Accurate, reliable prototype earth horizon sensor head
NASA Technical Reports Server (NTRS)
Schwarz, F.; Cohen, H.
1973-01-01
The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...
Important Nearby Galaxies without Accurate Distances
NASA Astrophysics Data System (ADS)
McQuinn, Kristen
2014-10-01
The Spitzer Infrared Nearby Galaxies Survey (SINGS) and its offspring programs (e.g., THINGS, HERACLES, KINGFISH) have resulted in a fundamental change in our view of star formation and the ISM in galaxies, and together they represent the most complete multi-wavelength data set yet assembled for a large sample of nearby galaxies. These great investments of observing time have been dedicated to the goal of understanding the interstellar medium, the star formation process, and, more generally, galactic evolution at the present epoch. Nearby galaxies provide the basis for which we interpret the distant universe, and the SINGS sample represents the best studied nearby galaxies.Accurate distances are fundamental to interpreting observations of galaxies. Surprisingly, many of the SINGS spiral galaxies have numerous distance estimates resulting in confusion. We can rectify this situation for 8 of the SINGS spiral galaxies within 10 Mpc at a very low cost through measurements of the tip of the red giant branch. The proposed observations will provide an accuracy of better than 0.1 in distance modulus. Our sample includes such well known galaxies as M51 (the Whirlpool), M63 (the Sunflower), M104 (the Sombrero), and M74 (the archetypal grand design spiral).We are also proposing coordinated parallel WFC3 UV observations of the central regions of the galaxies, rich with high-mass UV-bright stars. As a secondary science goal we will compare the resolved UV stellar populations with integrated UV emission measurements used in calibrating star formation rates. Our observations will complement the growing HST UV atlas of high resolution images of nearby galaxies.
Towards an accurate bioimpedance identification
NASA Astrophysics Data System (ADS)
Sanchez, B.; Louarroudi, E.; Bragos, R.; Pintelon, R.
2013-04-01
This paper describes the local polynomial method (LPM) for estimating the time-invariant bioimpedance frequency response function (FRF) considering both the output-error (OE) and the errors-in-variables (EIV) identification framework and compare it with the traditional cross— and autocorrelation spectral analysis techniques. The bioimpedance FRF is measured with the multisine electrical impedance spectroscopy (EIS) technique. To show the overwhelming accuracy of the LPM approach, both the LPM and the classical cross— and autocorrelation spectral analysis technique are evaluated through the same experimental data coming from a nonsteady-state measurement of time-varying in vivo myocardial tissue. The estimated error sources at the measurement frequencies due to noise, σnZ, and the stochastic nonlinear distortions, σZNL, have been converted to Ω and plotted over the bioimpedance spectrum for each framework. Ultimately, the impedance spectra have been fitted to a Cole impedance model using both an unweighted and a weighted complex nonlinear least square (CNLS) algorithm. A table is provided with the relative standard errors on the estimated parameters to reveal the importance of which system identification frameworks should be used.
Describing variations of the Fisher-matrix across parameter space
NASA Astrophysics Data System (ADS)
Schäfer, Björn Malte; Reischke, Robert
2016-08-01
Forecasts in cosmology, both with Monte Carlo Markov-chain methods and with the Fisher-matrix formalism, depend on the choice of the fiducial model because both the signal strength of any observable and the model non-linearities linking observables to cosmological parameters vary in the general case. In this paper we propose a method for extrapolating Fisher-forecasts across the space of cosmological parameters by constructing a suitable basis. We demonstrate the validity of our method with constraints on a standard dark energy model extrapolated from a ΛCDM-model, as can be expected from two-bin weak lensing tomography with an Euclid-like survey, in the parameter pairs (Ωm, σ8), (Ωm, w0) and (w0, wa). Our numerical results include very accurate extrapolations across a wide range of cosmological parameters in terms of shape, size and orientation of the parameter likelihood, and a decomposition of the change of the likelihood contours into modes, which are straightforward to interpret in a geometrical way. We find that in particular the variation of the dark energy figure of merit is well captured by our formalism.
A Self-Instructional Device for Conditioning Accurate Prosody.
ERIC Educational Resources Information Center
Buiten, Roger; Lane, Harlan
1965-01-01
A self-instructional device for conditioning accurate prosody in second-language learning is described in this article. The Speech Auto-Instructional Device (SAID) is electro-mechanical and performs three functions: SAID (1) presents to the student tape-recorded pattern sentences that are considered standards in prosodic performance; (2) processes…
The KFM, A Homemade Yet Accurate and Dependable Fallout Meter
Kearny, C.H.
2001-11-20
The KFM is a homemade fallout meter that can be made using only materials, tools, and skills found in millions of American homes. It is an accurate and dependable electroscope-capacitor. The KFM, in conjunction with its attached table and a watch, is designed for use as a rate meter. Its attached table relates observed differences in the separations of its two leaves (before and after exposures at the listed time intervals) to the dose rates during exposures of these time intervals. In this manner dose rates from 30 mR/hr up to 43 R/hr can be determined with an accuracy of {+-}25%. A KFM can be charged with any one of the three expedient electrostatic charging devices described. Due to the use of anhydrite (made by heating gypsum from wallboard) inside a KFM and the expedient ''dry-bucket'' in which it can be charged when the air is very humid, this instrument always can be charged and used to obtain accurate measurements of gamma radiation no matter how high the relative humidity. The heart of this report is the step-by-step illustrated instructions for making and using a KFM. These instructions have been improved after each successive field test. The majority of the untrained test families, adequately motivated by cash bonuses offered for success and guided only by these written instructions, have succeeded in making and using a KFM. NOTE: ''The KFM, A Homemade Yet Accurate and Dependable Fallout Meter'', was published by Oak Ridge National Laboratory report in1979. Some of the materials originally suggested for suspending the leaves of the Kearny Fallout Meter (KFM) are no longer available. Because of changes in the manufacturing process, other materials (e.g., sewing thread, unwaxed dental floss) may not have the insulating capability to work properly. Oak Ridge National Laboratory has not tested any of the suggestions provided in the preface of the report, but they have been used by other groups. When using these instructions, the builder can verify the
Development and testing of conceptual models describing plutonium subsurface transport (Invited)
NASA Astrophysics Data System (ADS)
Powell, B. A.
2009-12-01
, a conceptual model describing the effects of plutonium redox cycling on subsurface transport was developed. This model accurately described downward movement of plutonium in a series of field lysimeters. Research related to these lysimeters has continued using a combination of long-term field observations, laboratory measurements, and computer modeling which have provided a unique and detailed conceptual and quantitative model describing plutonium subsurface transport. Field and laboratory experiments indicate that biogeochemical processes such as ligand complexation and redox cycling profoundly influence plutonium subsurface transport. This presentation will focus on laboratory efforts to develop these conceptual models and provide a quantitative framework for reactive transport modeling efforts.
Diffusion model to describe osteogenesis within a porous titanium scaffold.
Schmitt, M; Allena, R; Schouman, T; Frasca, S; Collombet, J M; Holy, X; Rouch, P
2016-01-01
In this study, we develop a two-dimensional finite element model, which is derived from an animal experiment and allows simulating osteogenesis within a porous titanium scaffold implanted in ewe's hemi-mandible during 12 weeks. The cell activity is described through diffusion equations and regulated by the stress state of the structure. We compare our model to (i) histological observations and (ii) experimental data obtained from a mechanical test done on sacrificed animal. We show that our mechano-biological approach provides consistent numerical results and constitutes a useful tool to predict osteogenesis pattern. PMID:25573031
Quark and lepton mass matrices described by charged lepton masses
NASA Astrophysics Data System (ADS)
Koide, Yoshio; Nishiura, Hiroyuki
2016-06-01
Recently, we proposed a unified mass matrix model for quarks and leptons, in which, mass ratios and mixings of the quarks and neutrinos are described by using only the observed charged lepton mass values as family-number-dependent parameters and only six family-number-independent free parameters. In spite of quite few parameters, the model gives remarkable agreement with observed data (i.e. Cabibbo-Kobayashi-Maskawa (CKM) mixing, Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing and mass ratios). Taking this phenomenological success seriously, we give a formulation of the so-called Yukawaon model in detail from a theoretical aspect, especially for the construction of superpotentials and R charge assignments of fields. The model is considerably modified from the previous one, while the phenomenological success is kept unchanged.
Accurate lineshape spectroscopy and the Boltzmann constant
Truong, G.-W.; Anstie, J. D.; May, E. F.; Stace, T. M.; Luiten, A. N.
2015-01-01
Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here, we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a very accurate measurement of the excited-state (6P1/2) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity dispersion of the Cs vapour with an uncertainty of 35 p.p.m. within an hour. This allows us to determine a value for Boltzmann's constant with a precision of 6 p.p.m., and an uncertainty of 71 p.p.m. PMID:26465085
MEMS accelerometers in accurate mount positioning systems
NASA Astrophysics Data System (ADS)
Mészáros, László; Pál, András.; Jaskó, Attila
2014-07-01
In order to attain precise, accurate and stateless positioning of telescope mounts we apply microelectromechanical accelerometer systems (also known as MEMS accelerometers). In common practice, feedback from the mount position is provided by electronic, optical or magneto-mechanical systems or via real-time astrometric solution based on the acquired images. Hence, MEMS-based systems are completely independent from these mechanisms. Our goal is to investigate the advantages and challenges of applying such devices and to reach the sub-arcminute range { that is well smaller than the field-of-view of conventional imaging telescope systems. We present how this sub-arcminute accuracy can be achieved with very cheap MEMS sensors. Basically, these sensors yield raw output within an accuracy of a few degrees. We show what kind of calibration procedures could exploit spherical and cylindrical constraints between accelerometer output channels in order to achieve the previously mentioned accuracy level. We also demonstrate how can our implementation be inserted in a telescope control system. Although this attainable precision is less than both the resolution of telescope mount drive mechanics and the accuracy of astrometric solutions, the independent nature of attitude determination could significantly increase the reliability of autonomous or remotely operated astronomical observations.
Accurate lineshape spectroscopy and the Boltzmann constant.
Truong, G-W; Anstie, J D; May, E F; Stace, T M; Luiten, A N
2015-01-01
Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here, we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a very accurate measurement of the excited-state (6P1/2) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity dispersion of the Cs vapour with an uncertainty of 35 p.p.m. within an hour. This allows us to determine a value for Boltzmann's constant with a precision of 6 p.p.m., and an uncertainty of 71 p.p.m. PMID:26465085
Accurate Measurements of the Local Deuterium Abundance from HST Spectra
NASA Technical Reports Server (NTRS)
Linsky, Jeffrey L.
1996-01-01
An accurate measurement of the primordial value of D/H would provide a critical test of nucleosynthesis models for the early universe and the baryon density. I briefly summarize the ongoing HST observations of the interstellar H and D Lyman-alpha absorption for lines of sight to nearby stars and comment on recent reports of extragalactic D/H measurements.
Can the Non-linear Ballooning Model describe ELMs?
NASA Astrophysics Data System (ADS)
Henneberg, S. A.; Cowley, S. C.; Wilson, H. R.
2015-11-01
The explosive, filamentary plasma eruptions described by the non-linear ideal MHD ballooning model is tested quantitatively against experimental observations of ELMs in MAST. The equations describing this model were derived by Wilson and Cowley for tokamak-like geometry which includes two differential equations: the linear ballooning equation which describes the spatial distribution along the field lines and the non-linear ballooning mode envelope equation, which is a two-dimensional, non-linear differential equation which can involve fractional temporal-derivatives, but is often second-order in time and space. To employ the second differential equation for a specific geometry one has to evaluate the coefficients of the equation which is non-trivial as it involves field line averaging of slowly converging functions. We have solved this system for MAST, superimposing the solutions of both differential equations and mapping them onto a MAST plasma. Comparisons with the evolution of ELM filaments in MAST will be reported in order to test the model. The support of the EPSRC for the FCDT (Grant EP/K504178/1), of Euratom research and training programme 2014-2018 (No 633053) and of the RCUK Energy Programme [grant number EP/I501045] is gratefully acknowledged.
Differential equation based method for accurate approximations in optimization
NASA Technical Reports Server (NTRS)
Pritchard, Jocelyn I.; Adelman, Howard M.
1990-01-01
A method to efficiently and accurately approximate the effect of design changes on structural response is described. The key to this method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in most cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacements are used to approximate bending stresses.
Accurate paleointensities - the multi-method approach
NASA Astrophysics Data System (ADS)
de Groot, Lennart
2016-04-01
The accuracy of models describing rapid changes in the geomagnetic field over the past millennia critically depends on the availability of reliable paleointensity estimates. Over the past decade methods to derive paleointensities from lavas (the only recorder of the geomagnetic field that is available all over the globe and through geologic times) have seen significant improvements and various alternative techniques were proposed. The 'classical' Thellier-style approach was optimized and selection criteria were defined in the 'Standard Paleointensity Definitions' (Paterson et al, 2014). The Multispecimen approach was validated and the importance of additional tests and criteria to assess Multispecimen results must be emphasized. Recently, a non-heating, relative paleointensity technique was proposed -the pseudo-Thellier protocol- which shows great potential in both accuracy and efficiency, but currently lacks a solid theoretical underpinning. Here I present work using all three of the aforementioned paleointensity methods on suites of young lavas taken from the volcanic islands of Hawaii, La Palma, Gran Canaria, Tenerife, and Terceira. Many of the sampled cooling units are <100 years old, the actual field strength at the time of cooling is therefore reasonably well known. Rather intuitively, flows that produce coherent results from two or more different paleointensity methods yield the most accurate estimates of the paleofield. Furthermore, the results for some flows pass the selection criteria for one method, but fail in other techniques. Scrutinizing and combing all acceptable results yielded reliable paleointensity estimates for 60-70% of all sampled cooling units - an exceptionally high success rate. This 'multi-method paleointensity approach' therefore has high potential to provide the much-needed paleointensities to improve geomagnetic field models for the Holocene.
Observer Use of Standardized Observation Protocols in Consequential Observation Systems
ERIC Educational Resources Information Center
Bell, Courtney A.; Yi, Qi; Jones, Nathan D.; Lewis, Jennifer M.; McLeod, Monica; Liu, Shuangshuang
2014-01-01
Evidence from a handful of large-scale studies suggests that although observers can be trained to score reliably using observation protocols, there are concerns related to initial training and calibration activities designed to keep observers scoring accurately over time (e.g., Bell, et al, 2012; BMGF, 2012). Studies offer little insight into how…
Specific Heat Anomalies in Solids Described by a Multilevel Model
NASA Astrophysics Data System (ADS)
Souza, Mariano de; Paupitz, Ricardo; Seridonio, Antonio; Lagos, Roberto E.
2016-04-01
In the field of condensed matter physics, specific heat measurements can be considered as a pivotal experimental technique for characterizing the fundamental excitations involved in a certain phase transition. Indeed, phase transitions involving spin (de Souza et al. Phys. B Condens. Matter 404, 494 (2009) and Manna et al. Phys. Rev. Lett. 104, 016403 (2010)), charge (Pregelj et al. Phys. Rev. B 82, 144438 (2010)), lattice (Jesche et al. Phys. Rev. B 81, 134525 (2010)) (phonons) and orbital degrees of freedom, the interplay between ferromagnetism and superconductivity (Jesche et al. Phys. Rev. B 86, 020501 (2012)), Schottky-like anomalies in doped compounds (Lagos et al. Phys. C Supercond. 309, 170 (1998)), electronic levels in finite correlated systems (Macedo and Lagos J. Magn. Magn. Mater. 226, 105 (2001)), among other features, can be captured by means of high-resolution calorimetry. Furthermore, the entropy change associated with a first-order phase transition, no matter its nature, can be directly obtained upon integrating the specific heat over T, i.e., C( T)/ T, in the temperature range of interest. Here, we report on a detailed analysis of the two-peak specific heat anomalies observed in several materials. Employing a simple multilevel model, varying the spacing between the energy levels Δ i = ( E i - E 0) and the degeneracy of each energy level g i , we derive the required conditions for the appearance of such anomalies. Our findings indicate that a ratio of {Δ }2/{Δ }1thickapprox 10 between the energy levels and a high degeneracy of one of the energy levels define the two-peaks regime in the specific heat. Our approach accurately matches recent experimental results. Furthermore, using a mean-field approach, we calculate the specific heat of a degenerate Schottky-like system undergoing a ferromagnetic (FM) phase transition. Our results reveal that as the degeneracy is increased the Schottky maximum in the specific heat becomes narrow while the peak
Mill profiler machines soft materials accurately
NASA Technical Reports Server (NTRS)
Rauschl, J. A.
1966-01-01
Mill profiler machines bevels, slots, and grooves in soft materials, such as styrofoam phenolic-filled cores, to any desired thickness. A single operator can accurately control cutting depths in contour or straight line work.
Remote balance weighs accurately amid high radiation
NASA Technical Reports Server (NTRS)
Eggenberger, D. N.; Shuck, A. B.
1969-01-01
Commercial beam-type balance, modified and outfitted with electronic controls and digital readout, can be remotely controlled for use in high radiation environments. This allows accurate weighing of breeder-reactor fuel pieces when they are radioactively hot.
Understanding the Code: keeping accurate records.
Griffith, Richard
2015-10-01
In his continuing series looking at the legal and professional implications of the Nursing and Midwifery Council's revised Code of Conduct, Richard Griffith discusses the elements of accurate record keeping under Standard 10 of the Code. This article considers the importance of accurate record keeping for the safety of patients and protection of district nurses. The legal implications of records are explained along with how district nurses should write records to ensure these legal requirements are met. PMID:26418404
A time-accurate multiple-grid algorithm
NASA Technical Reports Server (NTRS)
Jespersen, D. C.
1985-01-01
A time-accurate multiple-grid algorithm is described. The algorithm allows one to take much larger time steps with an explicit time-marching scheme than would otherwise be the case. Sample calculations of a scalar advection equation and the Euler equations for an oscillating airfoil are shown. For the oscillating airfoil, time steps an order of magnitude larger than the single-grid algorithm are possible.
Accurate Insertion Loss Measurements of the Juno Patch Array Antennas
NASA Technical Reports Server (NTRS)
Chamberlain, Neil; Chen, Jacqueline; Hodges, Richard; Demas, John
2010-01-01
This paper describes two independent methods for estimating the insertion loss of patch array antennas that were developed for the Juno Microwave Radiometer instrument. One method is based principally on pattern measurements while the other method is based solely on network analyzer measurements. The methods are accurate to within 0.1 dB for the measured antennas and show good agreement (to within 0.1dB) of separate radiometric measurements.
White, Peter A
2013-01-01
How accurate are explicit judgements about familiar forms of object motion, and how are they made? Participants judged the relations between force exerted in kicking a soccer ball and variables that define the trajectory of the ball: launch angle, maximum height attained, and maximum distance reached. Judgements tended to conform to a simple heuristic that judged force tends to increase as maximum height and maximum distance increase, with launch angle not being influential. Support was also found for the converse prediction, that judged maximum height and distance tend to increase as the amount of force described in the kick increases. The observed judgemental tendencies did not resemble the objective relations, in which force is a function of interactions between the trajectory variables. This adds to a body of research indicating that practical knowledge based on experiences of actions on objects is not available to the processes that generate judgements in higher cognition and that such judgements are generated by simple rules that do not capture the objective interactions between the physical variables. PMID:23075337
Quantization method for describing the motion of celestial systems
NASA Astrophysics Data System (ADS)
Christianto, Victor; Smarandache, Florentin
2015-11-01
Criticism arises concerning the use of quantization method for describing the motion of celestial systems, arguing that the method is oversimplifying the problem, and cannot explain other phenomena, for instance planetary migration. Using quantization method like Nottale-Schumacher did, one can expect to predict new exoplanets with remarkable result. The ``conventional'' theories explaining planetary migration normally use fluid theory involving diffusion process. Gibson have shown that these migration phenomena could be described via Navier-Stokes approach. Kiehn's argument was based on exact-mapping between Schrodinger equation and Navier-Stokes equations, while our method may be interpreted as an oversimplification of the real planetary migration process which took place sometime in the past, providing useful tool for prediction (e.g. other planetoids, which are likely to be observed in the near future, around 113.8AU and 137.7 AU). Therefore, quantization method could be seen as merely a ``plausible'' theory. We would like to emphasize that the quantization method does not have to be the true description of reality with regards to celestial phenomena. This method could explain some phenomena, while perhaps lacks explanation for other phenomena.
Asphere, O asphere, how shall we describe thee?
NASA Astrophysics Data System (ADS)
Forbes, G. W.; Brophy, C. P.
2008-09-01
Two key criteria govern the characterization of nominal shapes for aspheric optical surfaces. An efficient representation describes the spectrum of relevant shapes to the required accuracy by using the fewest decimal digits in the associated coefficients. Also, a representation is more effective if it can, in some way, facilitate other processes - such as optical design, tolerancing, or direct human interpretation. With the development of better tools for their design, metrology, and fabrication, aspheric optics are becoming ever more pervasive. As part of this trend, aspheric departures of up to a thousand microns or more must be characterized at almost nanometre precision. For all but the simplest of shapes, this is not as easy as it might sound. Efficiency is therefore increasingly important. Further, metrology tools continue to be one of the weaker links in the cost-effective production of aspheric optics. Interferometry particularly struggles to deal with steep slopes in aspheric departure. Such observations motivated the ideas described in what follows for modifying the conventional description of rotationally symmetric aspheres to use orthogonal bases that boost efficiency. The new representations can facilitate surface tolerancing as well as the design of aspheres with cost-effective metrology options. These ideas enable the description of aspheric shapes in terms of decompositions that not only deliver improved efficiency and effectiveness, but that are also shown to admit direct interpretations. While it's neither poetry nor a cure-all, an old blight can be relieved.
Accurate energy levels for singly ionized platinum (Pt II)
NASA Technical Reports Server (NTRS)
Reader, Joseph; Acquista, Nicolo; Sansonetti, Craig J.; Engleman, Rolf, Jr.
1988-01-01
New observations of the spectrum of Pt II have been made with hollow-cathode lamps. The region from 1032 to 4101 A was observed photographically with a 10.7-m normal-incidence spectrograph. The region from 2245 to 5223 A was observed with a Fourier-transform spectrometer. Wavelength measurements were made for 558 lines. The uncertainties vary from 0.0005 to 0.004 A. From these measurements and three parity-forbidden transitions in the infrared, accurate values were determined for 28 even and 72 odd energy levels of Pt II.
On the importance of having accurate data for astrophysical modelling
NASA Astrophysics Data System (ADS)
Lique, Francois
2016-06-01
The Herschel telescope and the ALMA and NOEMA interferometers have opened new windows of observation for wavelengths ranging from far infrared to sub-millimeter with spatial and spectral resolutions previously unmatched. To make the most of these observations, an accurate knowledge of the physical and chemical processes occurring in the interstellar and circumstellar media is essential.In this presentation, I will discuss what are the current needs of astrophysics in terms of molecular data and I will show that accurate molecular data are crucial for the proper determination of the physical conditions in molecular clouds.First, I will focus on collisional excitation studies that are needed for molecular lines modelling beyond the Local Thermodynamic Equilibrium (LTE) approach. In particular, I will show how new collisional data for the HCN and HNC isomers, two tracers of star forming conditions, have allowed solving the problem of their respective abundance in cold molecular clouds. I will also present the last collisional data that have been computed in order to analyse new highly resolved observations provided by the ALMA interferometer.Then, I will present the calculation of accurate rate constants for the F+H2 → HF+H and Cl+H2 ↔ HCl+H reactions, which have allowed a more accurate determination of the physical conditions in diffuse molecular clouds. I will also present the recent work on the ortho-para-H2 conversion due to hydrogen exchange that allow more accurate determination of the ortho-to-para-H2 ratio in the universe and that imply a significant revision of the cooling mechanism in astrophysical media.
Heuristics for scheduling Earth observing satellites
NASA Astrophysics Data System (ADS)
Wolfe, William J.; Sorensen, Stephen E.
1999-09-01
This paper describes several methods for assigning tasks to Earth Observing Systems Satellites (EOS). We present empirical results for three heuristics, called: Priority Dispatch (PD), Look Ahead (LA), and Genetic Algorithm (GA). These heuristics progress from simple to complex, from less accurate to more accurate, and from fast to slow. We present empirical results as applied to the Window-Constrained Packing problem (WCP). The WCP is a simplified version of the EOS scheduling problem. We discuss the problem of having more than one optimization criteria. We will also discuss the relationship between the WCP and the more traditional Knapsack and Weighted Early/Tardy problems.
Photoacoustic computed tomography without accurate ultrasonic transducer responses
NASA Astrophysics Data System (ADS)
Sheng, Qiwei; Wang, Kun; Xia, Jun; Zhu, Liren; Wang, Lihong V.; Anastasio, Mark A.
2015-03-01
Conventional photoacoustic computed tomography (PACT) image reconstruction methods assume that the object and surrounding medium are described by a constant speed-of-sound (SOS) value. In order to accurately recover fine structures, SOS heterogeneities should be quantified and compensated for during PACT reconstruction. To address this problem, several groups have proposed hybrid systems that combine PACT with ultrasound computed tomography (USCT). In such systems, a SOS map is reconstructed first via USCT. Consequently, this SOS map is employed to inform the PACT reconstruction method. Additionally, the SOS map can provide structural information regarding tissue, which is complementary to the functional information from the PACT image. We propose a paradigm shift in the way that images are reconstructed in hybrid PACT-USCT imaging. Inspired by our observation that information about the SOS distribution is encoded in PACT measurements, we propose to jointly reconstruct the absorbed optical energy density and SOS distributions from a combined set of USCT and PACT measurements, thereby reducing the two reconstruction problems into one. This innovative approach has several advantages over conventional approaches in which PACT and USCT images are reconstructed independently: (1) Variations in the SOS will automatically be accounted for, optimizing PACT image quality; (2) The reconstructed PACT and USCT images will possess minimal systematic artifacts because errors in the imaging models will be optimally balanced during the joint reconstruction; (3) Due to the exploitation of information regarding the SOS distribution in the full-view PACT data, our approach will permit high-resolution reconstruction of the SOS distribution from sparse array data.
An accurate geometric distance to the compact binary SS Cygni vindicates accretion disc theory.
Miller-Jones, J C A; Sivakoff, G R; Knigge, C; Körding, E G; Templeton, M; Waagen, E O
2013-05-24
Dwarf novae are white dwarfs accreting matter from a nearby red dwarf companion. Their regular outbursts are explained by a thermal-viscous instability in the accretion disc, described by the disc instability model that has since been successfully extended to other accreting systems. However, the prototypical dwarf nova, SS Cygni, presents a major challenge to our understanding of accretion disc theory. At the distance of 159 ± 12 parsecs measured by the Hubble Space Telescope, it is too luminous to be undergoing the observed regular outbursts. Using very long baseline interferometric radio observations, we report an accurate, model-independent distance to SS Cygni that places the source substantially closer at 114 ± 2 parsecs. This reconciles the source behavior with our understanding of accretion disc theory in accreting compact objects. PMID:23704566
NASA Astrophysics Data System (ADS)
Brown, D.
Very few cuneiform records survive from Mesopotamia of datable astronomical observations made prior to the mid-eighth century BC. Those that do record occasional eclipses, and in one isolated case the dates of the heliacal rising and setting of Venus over a few years sometime in the first half of the second millennium BC. After the mid-eighth century BC the situation changes dramatically. Incomplete records of daily observations of astronomical and meteorological events are preserved from c. 747 BC until the Christian Period. These records are without accompanying ominous interpretation, although it is highly probable that they were compiled by diviners for astrological purposes. They include numerous observations of use to historical astronomers, such as the times of eclipses and occultations, and the dates of comet appearances and meteor showers. The question arises as to why such records do not survive from earlier times; celestial divination was employed as far back as the third millenium BC. It is surely not without importance that the earliest known accurate astronomical predictions accompany the later records, and that the mid-eighth century BC ushered in a period of centralised Assyrian control of Mesopotamia and the concomitant employment by the Assyrian ruler of large numbers of professional celestial diviners. The programme of daily observations evidently began when a high premium was first set on the accurate astronomical prediction of ominous events. It is in this light that we must approach this valuable source material for historical astronomy.
ERIC Educational Resources Information Center
Rutherford, Heather
2011-01-01
This article describes how a teacher integrates science observations into the writing center. At the observation station, students explore new items with a science theme and use their notes and questions for class writings every day. Students are exposed to a variety of different topics and motivated to write in different styles all while…
A highly accurate interatomic potential for argon
NASA Astrophysics Data System (ADS)
Aziz, Ronald A.
1993-09-01
A modified potential based on the individually damped model of Douketis, Scoles, Marchetti, Zen, and Thakkar [J. Chem. Phys. 76, 3057 (1982)] is presented which fits, within experimental error, the accurate ultraviolet (UV) vibration-rotation spectrum of argon determined by UV laser absorption spectroscopy by Herman, LaRocque, and Stoicheff [J. Chem. Phys. 89, 4535 (1988)]. Other literature potentials fail to do so. The potential also is shown to predict a large number of other properties and is probably the most accurate characterization of the argon interaction constructed to date.
Issues with Describing the Uncertainties in Atmospheric Remote Sensing Measurements
NASA Astrophysics Data System (ADS)
Haffner, D. P.; Bhartia, P. K.; Kramarova, N. A.
2014-12-01
Uncertainty in atmospheric measurements from satellites and other remote sensing platforms comes from several sources. Users are familiar with concepts of accuracy and precision for physical measurements made using instrumentation, but retrieval algorithms also frequently require statistical information since measurements alone may not completely determine the parameter of interest. This statistical information has uncertainty associated with it as well, and it often contributes a sizeable fraction to the total uncertainty. The precise combination of physical and statistical information in remotely sensed data can vary with season, latitude, altitude, and conditions of measurement. While this picture is complex, it is important to clearly define the overall uncertainty for users without oversimplifying so they can interpret the data correctly. Assessment of trends, quantification of radiative forcing and chemical budgets, and comparisons of models with satellite observations all benefit from having adequate uncertainty information. But even today, terminology and interpretation of these uncertainties is a hot topic of discussion among experts. Based on our experience producing a 44 year-long dataset of total ozone and ozone profiles, we discuss our ideas for describing uncertainty in atmospheric datasets for global change research. Assumptions about the atmosphere used in retrievals can also be provided with exact information detailing how the final product depends on these assumptions. As a practical example, we discuss our modifications to the Total Ozone Mapping Spectrometer (TOMS) algorithm in Version 9 to provide robust uncertainties for each measurement and supply as much useful information to users as possible. Finally, we describe how uncertainties in individual measurements combine when the data are aggregated in time and space.
A six-parameter space to describe galaxy diversification
NASA Astrophysics Data System (ADS)
Fraix-Burnet, D.; Chattopadhyay, T.; Chattopadhyay, A. K.; Davoust, E.; Thuillard, M.
2012-09-01
Context. The diversification of galaxies is caused by transforming events such as accretion, interaction, or mergers. These explain the formation and evolution of galaxies, which can now be described by many observables. Multivariate analyses are the obvious tools to tackle the available datasets and understand the differences between different kinds of objects. However, depending on the method used, redundancies, incompatibilities, or subjective choices of the parameters can diminish the usefulness of these analyses. The behaviour of the available parameters should be analysed before any objective reduction in the dimensionality and any subsequent clustering analyses can be undertaken, especially in an evolutionary context. Aims: We study a sample of 424 early-type galaxies described by 25 parameters, 10 of which are Lick indices, to identify the most discriminant parameters and construct an evolutionary classification of these objects. Methods: Four independent statistical methods are used to investigate the discriminant properties of the observables and the partitioning of the 424 galaxies: principal component analysis, K-means cluster analysis, minimum contradiction analysis, and Cladistics. Results: The methods agree in terms of six parameters: central velocity dispersion, disc-to-bulge ratio, effective surface brightness, metallicity, and the line indices NaD and OIII. The partitioning found using these six parameters, when projected onto the fundamental plane, looks very similar to the partitioning obtained previously for a totally different sample and based only on the parameters of the fundamental plane. Two additional groups are identified here, and we are able to provide some more constraints on the assembly history of galaxies within each group thanks to the larger number of parameters. We also identify another "fundamental plane" with the absolute K magnitude, the linear diameter, and the Lick index Hβ. We confirm that the Mg b vs. velocity dispersion
Accurate pointing of tungsten welding electrodes
NASA Technical Reports Server (NTRS)
Ziegelmeier, P.
1971-01-01
Thoriated-tungsten is pointed accurately and quickly by using sodium nitrite. Point produced is smooth and no effort is necessary to hold the tungsten rod concentric. The chemically produced point can be used several times longer than ground points. This method reduces time and cost of preparing tungsten electrodes.
Inference of random walk models to describe leukocyte migration
NASA Astrophysics Data System (ADS)
Jones, Phoebe J. M.; Sim, Aaron; Taylor, Harriet B.; Bugeon, Laurence; Dallman, Magaret J.; Pereira, Bernard; Stumpf, Michael P. H.; Liepe, Juliane
2015-12-01
While the majority of cells in an organism are static and remain relatively immobile in their tissue, migrating cells occur commonly during developmental processes and are crucial for a functioning immune response. The mode of migration has been described in terms of various types of random walks. To understand the details of the migratory behaviour we rely on mathematical models and their calibration to experimental data. Here we propose an approximate Bayesian inference scheme to calibrate a class of random walk models characterized by a specific, parametric particle re-orientation mechanism to observed trajectory data. We elaborate the concept of transition matrices (TMs) to detect random walk patterns and determine a statistic to quantify these TM to make them applicable for inference schemes. We apply the developed pipeline to in vivo trajectory data of macrophages and neutrophils, extracted from zebrafish that had undergone tail transection. We find that macrophage and neutrophils exhibit very distinct biased persistent random walk patterns, where the strengths of the persistence and bias are spatio-temporally regulated. Furthermore, the movement of macrophages is far less persistent than that of neutrophils in response to wounding.
Inference of random walk models to describe leukocyte migration.
Jones, Phoebe J M; Sim, Aaron; Taylor, Harriet B; Bugeon, Laurence; Dallman, Magaret J; Pereira, Bernard; Stumpf, Michael P H; Liepe, Juliane
2015-12-01
While the majority of cells in an organism are static and remain relatively immobile in their tissue, migrating cells occur commonly during developmental processes and are crucial for a functioning immune response. The mode of migration has been described in terms of various types of random walks. To understand the details of the migratory behaviour we rely on mathematical models and their calibration to experimental data. Here we propose an approximate Bayesian inference scheme to calibrate a class of random walk models characterized by a specific, parametric particle re-orientation mechanism to observed trajectory data. We elaborate the concept of transition matrices (TMs) to detect random walk patterns and determine a statistic to quantify these TM to make them applicable for inference schemes. We apply the developed pipeline to in vivo trajectory data of macrophages and neutrophils, extracted from zebrafish that had undergone tail transection. We find that macrophage and neutrophils exhibit very distinct biased persistent random walk patterns, where the strengths of the persistence and bias are spatio-temporally regulated. Furthermore, the movement of macrophages is far less persistent than that of neutrophils in response to wounding. PMID:26403334
A Method for Accurate in silico modeling of Ultrasound Transducer Arrays
Guenther, Drake A.; Walker, William F.
2009-01-01
This paper presents a new approach to improve the in silico modeling of ultrasound transducer arrays. While current simulation tools accurately predict the theoretical element spatio-temporal pressure response, transducers do not always behave as theorized. In practice, using the probe's physical dimensions and published specifications in silico, often results in unsatisfactory agreement between simulation and experiment. We describe a general optimization procedure used to maximize the correlation between the observed and simulated spatio-temporal response of a pulsed single element in a commercial ultrasound probe. A linear systems approach is employed to model element angular sensitivity, lens effects, and diffraction phenomena. A numerical deconvolution method is described to characterize the intrinsic electro-mechanical impulse response of the element. Once the response of the element and optimal element characteristics are known, prediction of the pressure response for arbitrary apertures and excitation signals is performed through direct convolution using available tools. We achieve a correlation of 0.846 between the experimental emitted waveform and simulated waveform when using the probe's physical specifications in silico. A far superior correlation of 0.988 is achieved when using the optimized in silico model. Electronic noise appears to be the main effect preventing the realization of higher correlation coefficients. More accurate in silico modeling will improve the evaluation and design of ultrasound transducers as well as aid in the development of sophisticated beamforming strategies. PMID:19041997
Accurate nuclear radii and binding energies from a chiral interaction
Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold
2015-05-01
With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shellmore » nuclei are in reasonable agreement with experiment.« less
Method for Accurately Calibrating a Spectrometer Using Broadband Light
NASA Technical Reports Server (NTRS)
Simmons, Stephen; Youngquist, Robert
2011-01-01
A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.
Accurate nuclear radii and binding energies from a chiral interaction
Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold
2015-05-01
With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLO_{sat}, yield accurate binding energies and radii of nuclei up to ^{40}Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective J^{π}=3^{-} states in ^{16}O and ^{40}Ca are described accurately, while spectra for selected p- and sd-shell nuclei are in reasonable agreement with experiment.
Optical Chopper Assembly for the Mars Observer
NASA Technical Reports Server (NTRS)
Allen, Terry
1993-01-01
This paper describes the Honeywell-developed Optical Chopper Assembly (OCA), a component of Mars Observer spacecraft's Pressure Modulator Infrared Radiometer (PMIRR) science experiment, which will map the Martian atmosphere during 1993 to 1995. The OCA is unique because of its constant accurate rotational speed, low electrical power consumption, and long-life requirements. These strict and demanding requirements were achieved by use of a number of novel approaches.
ERIC Educational Resources Information Center
Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi
2012-01-01
One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected by feedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On Day 1, participants performed a golf putting task under one of…
Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi
2012-06-01
One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected byfeedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On day 1, participants performed a golf putting task under one of two conditions: one group received feedback on the most accurate trials, whereas another group received feedback on the least accurate trials. On day 2, participants completed an anxiety questionnaire and performed a retention test. Shin conductance level, as a measure of arousal, was determined. The results indicated that feedback about more accurate trials resulted in more effective learning as well as increased self-confidence. Also, activation was a predictor of performance. PMID:22808705
New model accurately predicts reformate composition
Ancheyta-Juarez, J.; Aguilar-Rodriguez, E. )
1994-01-31
Although naphtha reforming is a well-known process, the evolution of catalyst formulation, as well as new trends in gasoline specifications, have led to rapid evolution of the process, including: reactor design, regeneration mode, and operating conditions. Mathematical modeling of the reforming process is an increasingly important tool. It is fundamental to the proper design of new reactors and revamp of existing ones. Modeling can be used to optimize operating conditions, analyze the effects of process variables, and enhance unit performance. Instituto Mexicano del Petroleo has developed a model of the catalytic reforming process that accurately predicts reformate composition at the higher-severity conditions at which new reformers are being designed. The new AA model is more accurate than previous proposals because it takes into account the effects of temperature and pressure on the rate constants of each chemical reaction.
Accurate colorimetric feedback for RGB LED clusters
NASA Astrophysics Data System (ADS)
Man, Kwong; Ashdown, Ian
2006-08-01
We present an empirical model of LED emission spectra that is applicable to both InGaN and AlInGaP high-flux LEDs, and which accurately predicts their relative spectral power distributions over a wide range of LED junction temperatures. We further demonstrate with laboratory measurements that changes in LED spectral power distribution with temperature can be accurately predicted with first- or second-order equations. This provides the basis for a real-time colorimetric feedback system for RGB LED clusters that can maintain the chromaticity of white light at constant intensity to within +/-0.003 Δuv over a range of 45 degrees Celsius, and to within 0.01 Δuv when dimmed over an intensity range of 10:1.
Accurate mask model for advanced nodes
NASA Astrophysics Data System (ADS)
Zine El Abidine, Nacer; Sundermann, Frank; Yesilada, Emek; Ndiaye, El Hadji Omar; Mishra, Kushlendra; Paninjath, Sankaranarayanan; Bork, Ingo; Buck, Peter; Toublan, Olivier; Schanen, Isabelle
2014-07-01
Standard OPC models consist of a physical optical model and an empirical resist model. The resist model compensates the optical model imprecision on top of modeling resist development. The optical model imprecision may result from mask topography effects and real mask information including mask ebeam writing and mask process contributions. For advanced technology nodes, significant progress has been made to model mask topography to improve optical model accuracy. However, mask information is difficult to decorrelate from standard OPC model. Our goal is to establish an accurate mask model through a dedicated calibration exercise. In this paper, we present a flow to calibrate an accurate mask enabling its implementation. The study covers the different effects that should be embedded in the mask model as well as the experiment required to model them.
Accurate guitar tuning by cochlear implant musicians.
Lu, Thomas; Huang, Juan; Zeng, Fan-Gang
2014-01-01
Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼ 30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task. PMID:24651081
Two highly accurate methods for pitch calibration
NASA Astrophysics Data System (ADS)
Kniel, K.; Härtig, F.; Osawa, S.; Sato, O.
2009-11-01
Among profiles, helix and tooth thickness pitch is one of the most important parameters of an involute gear measurement evaluation. In principle, coordinate measuring machines (CMM) and CNC-controlled gear measuring machines as a variant of a CMM are suited for these kinds of gear measurements. Now the Japan National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and the German national metrology institute the Physikalisch-Technische Bundesanstalt (PTB) have each developed independently highly accurate pitch calibration methods applicable to CMM or gear measuring machines. Both calibration methods are based on the so-called closure technique which allows the separation of the systematic errors of the measurement device and the errors of the gear. For the verification of both calibration methods, NMIJ/AIST and PTB performed measurements on a specially designed pitch artifact. The comparison of the results shows that both methods can be used for highly accurate calibrations of pitch standards.
Accurate modeling of parallel scientific computations
NASA Technical Reports Server (NTRS)
Nicol, David M.; Townsend, James C.
1988-01-01
Scientific codes are usually parallelized by partitioning a grid among processors. To achieve top performance it is necessary to partition the grid so as to balance workload and minimize communication/synchronization costs. This problem is particularly acute when the grid is irregular, changes over the course of the computation, and is not known until load time. Critical mapping and remapping decisions rest on the ability to accurately predict performance, given a description of a grid and its partition. This paper discusses one approach to this problem, and illustrates its use on a one-dimensional fluids code. The models constructed are shown to be accurate, and are used to find optimal remapping schedules.
Accurate Guitar Tuning by Cochlear Implant Musicians
Lu, Thomas; Huang, Juan; Zeng, Fan-Gang
2014-01-01
Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task. PMID:24651081
Accurate maser positions for MALT-45
NASA Astrophysics Data System (ADS)
Jordan, Christopher; Bains, Indra; Voronkov, Maxim; Lo, Nadia; Jones, Paul; Muller, Erik; Cunningham, Maria; Burton, Michael; Brooks, Kate; Green, James; Fuller, Gary; Barnes, Peter; Ellingsen, Simon; Urquhart, James; Morgan, Larry; Rowell, Gavin; Walsh, Andrew; Loenen, Edo; Baan, Willem; Hill, Tracey; Purcell, Cormac; Breen, Shari; Peretto, Nicolas; Jackson, James; Lowe, Vicki; Longmore, Steven
2013-10-01
MALT-45 is an untargeted survey, mapping the Galactic plane in CS (1-0), Class I methanol masers, SiO masers and thermal emission, and high frequency continuum emission. After obtaining images from the survey, a number of masers were detected, but without accurate positions. This project seeks to resolve each maser and its environment, with the ultimate goal of placing the Class I methanol maser into a timeline of high mass star formation.
Describing phase coexistence in systems with small phases
NASA Astrophysics Data System (ADS)
Lovett, R.
2007-02-01
Clusters of atoms can be studied in molecular beams and by computer simulation; 'liquid drops' provide elementary models for atomic nuclei and for the critical nuclei of nucleation theory. These clusters are often described in thermodynamic terms, but the behaviour of small clusters near a phase boundary is qualitatively different from the behaviour at a first order phase transition in idealized thermodynamics. In the idealized case the density and entropy show mathematically sharp discontinuities when the phase boundary is crossed. In large, but finite, systems, the phase boundaries become regions of state space wherein these properties vary rapidly but continuously. In small clusters with a large surface/volume ratio, however, the positive interfacial free energy makes it unlikely, even in states on phase boundaries, that a cluster will have a heterogeneous structure. What is actually seen in these states is a structure that fluctuates in time between homogeneous structures characteristic of the two sides of the phase boundary. That is, structural fluctuations are observed. Thermodynamics only predicts average properties; statistical mechanics is required to understand these fluctuations. Failure to distinguish thermodynamic properties and characterizations of fluctuations, particularly in the context of first order phase transitions, has led to suggestions that the classical rules for thermodynamic stability are violated in small systems and that classical thermodynamics provides an inconsistent description of these systems. Much of the confusion stems from taking statistical mechanical identifications of thermodynamic properties, explicitly developed for large systems, and applying them uncritically to small systems. There are no inconsistencies if thermodynamic properties are correctly identified and the distinction between thermodynamic properties and fluctuations is made clear.
Accurate phase-shift velocimetry in rock.
Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M
2016-06-01
Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models. PMID:27111139
Accurate Molecular Polarizabilities Based on Continuum Electrostatics
Truchon, Jean-François; Nicholls, Anthony; Iftimie, Radu I.; Roux, Benoît; Bayly, Christopher I.
2013-01-01
A novel approach for representing the intramolecular polarizability as a continuum dielectric is introduced to account for molecular electronic polarization. It is shown, using a finite-difference solution to the Poisson equation, that the Electronic Polarization from Internal Continuum (EPIC) model yields accurate gas-phase molecular polarizability tensors for a test set of 98 challenging molecules composed of heteroaromatics, alkanes and diatomics. The electronic polarization originates from a high intramolecular dielectric that produces polarizabilities consistent with B3LYP/aug-cc-pVTZ and experimental values when surrounded by vacuum dielectric. In contrast to other approaches to model electronic polarization, this simple model avoids the polarizability catastrophe and accurately calculates molecular anisotropy with the use of very few fitted parameters and without resorting to auxiliary sites or anisotropic atomic centers. On average, the unsigned error in the average polarizability and anisotropy compared to B3LYP are 2% and 5%, respectively. The correlation between the polarizability components from B3LYP and this approach lead to a R2 of 0.990 and a slope of 0.999. Even the F2 anisotropy, shown to be a difficult case for existing polarizability models, can be reproduced within 2% error. In addition to providing new parameters for a rapid method directly applicable to the calculation of polarizabilities, this work extends the widely used Poisson equation to areas where accurate molecular polarizabilities matter. PMID:23646034
Accurate phase-shift velocimetry in rock
NASA Astrophysics Data System (ADS)
Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R.; Holmes, William M.
2016-06-01
Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.
New Techniques and Metrics for Describing Rivers Using High Resolution Digital Elevation Models
NASA Astrophysics Data System (ADS)
Bailey, P.; McKean, J. A.; Poulsen, F.; Ochoski, N.; Wheaton, J. M.
2013-12-01
Techniques for collecting high resolution digital elevation models (DEMs) of fluvial environments are cheaper and more widely accessible than ever before. These DEMs improve over traditional transect-based approaches because they represent the channel bed as a continuous surface. Advantages beyond the obvious more accurate representations of channel area and volume include the three dimensional representation of geomorphic features that directly influence the behavior of river organisms. It is possible to identify many of these habitats using topography alone, but when combined with the spatial arrangement of these areas within the channel, a more holistic view of biologic existence can be gleaned from the three dimensional representation of the channel. We present a new approach for measuring and describing channels that leverages the continuous nature of digital elevation model surfaces. Delivered via the River Bathymetry Toolkit (RBT) this approach is capable of not only reproducing the traditional transect-based metrics, but also includes novel techniques for generating stage independent channel measurements, regardless of the flow that occurred at the time of data capture. The RBT also possesses the capability of measuring changes over time, accounting for uncertainty using approaches adopted from the Geomorphic Change Detection (GCD) literature and producing maps and metrics for erosion and deposition. This new approach is available via the River Bathymetry Toolit that is structured to enable repeat systematic measurements over an unlimited number of sites. We present how this approach has been applied to over 500 sites in the Pacific Northwest as part of the Columbia Habitat Mapping Program (CHaMP). We demonstrate the new channel metrics for a range of these sites, both at the observed and simulated flows as well as examples of changes in channel morphology over time. We present an analysis comparing these new metrics against traditional transect based
NASA Astrophysics Data System (ADS)
Del Giudice, Dario; Albert, Carlo; Rieckermann, Jörg; Reichert, Peter
2016-04-01
Rainfall input uncertainty is one of the major concerns in hydrological modeling. Unfortunately, during inference, input errors are usually neglected, which can lead to biased parameters and implausible predictions. Rainfall multipliers can reduce this problem but still fail when the observed input (precipitation) has a different temporal pattern from the true one or if the true nonzero input is not detected. In this study, we propose an improved input error model which is able to overcome these challenges and to assess and reduce input uncertainty. We formulate the average precipitation over the watershed as a stochastic input process (SIP) and, together with a model of the hydrosystem, include it in the likelihood function. During statistical inference, we use "noisy" input (rainfall) and output (runoff) data to learn about the "true" rainfall, model parameters, and runoff. We test the methodology with the rainfall-discharge dynamics of a small urban catchment. To assess its advantages, we compare SIP with simpler methods of describing uncertainty within statistical inference: (i) standard least squares (LS), (ii) bias description (BD), and (iii) rainfall multipliers (RM). We also compare two scenarios: accurate versus inaccurate forcing data. Results show that when inferring the input with SIP and using inaccurate forcing data, the whole-catchment precipitation can still be realistically estimated and thus physical parameters can be "protected" from the corrupting impact of input errors. While correcting the output rather than the input, BD inferred similarly unbiased parameters. This is not the case with LS and RM. During validation, SIP also delivers realistic uncertainty intervals for both rainfall and runoff. Thus, the technique presented is a significant step toward better quantifying input uncertainty in hydrological inference. As a next step, SIP will have to be combined with a technique addressing model structure uncertainty.
NASA Astrophysics Data System (ADS)
Mattsson, Ann E.; Wills, John M.
2013-03-01
The inability to computationally describe the physics governing the properties of actinides and their alloys is the poster child of failure of existing Density Functional Theory exchange-correlation functionals. The intricate competition between localization and delocalization of the electrons, present in these materials, exposes the limitations of functionals only designed to properly describe one or the other situation. We will discuss the manifestation of this competition in real materials and propositions on how to construct a functional able to accurately describe properties of these materials. I addition we will discuss both the importance of using the Dirac equation to describe the relativistic effects in these materials, and the connection to the physics of transition metal oxides. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
High Frequency QRS ECG Accurately Detects Cardiomyopathy
NASA Technical Reports Server (NTRS)
Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds
2005-01-01
High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing
Damage and fatigue described by a fractional derivative model
NASA Astrophysics Data System (ADS)
Caputo, Michele; Fabrizio, Mauro
2015-07-01
As in [1], damage is associated with fatigue that a material undergoes. In this paper, because we work with viscoelastic solids represented by a fractional model, damage is described by the order of the fractional derivative, which represents the phase field satisfying Ginzburg-Landau equation, which describes the evolution of damage. Finally, in our model, damage is caused, not only by fatigue, but also directly by a source related to environmental factors and described by a positive time function.
Accurate thermoelastic tensor and acoustic velocities of NaCl
NASA Astrophysics Data System (ADS)
Marcondes, Michel L.; Shukla, Gaurav; da Silveira, Pedro; Wentzcovitch, Renata M.
2015-12-01
Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.
Differential equation based method for accurate approximations in optimization
NASA Technical Reports Server (NTRS)
Pritchard, Jocelyn I.; Adelman, Howard M.
1990-01-01
This paper describes a method to efficiently and accurately approximate the effect of design changes on structural response. The key to this new method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in msot cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacement are used to approximate bending stresses.
Accurate thermoelastic tensor and acoustic velocities of NaCl
Marcondes, Michel L.; Shukla, Gaurav; Silveira, Pedro da; Wentzcovitch, Renata M.
2015-12-15
Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.
Describing Communicative Functions in a First Grade Classroom.
ERIC Educational Resources Information Center
Wrather, Nancy
The purpose of this study was to synthesize a category system for observation of communicative functions in children's speech and to test that category system by recording observations of interactions within a first-grade classroom. The observation system which was designed attempts to account for all factors of a communication situation and to…
Describing function theory as applied to thermal and neutronic problems
Nassersharif, B.
1983-01-01
Describing functions have traditionally been used to obtain the solutions of systems of ordinary differential equations. In this work the describing function concept has been extended to include nonlinear, distributed parameter partial differential equations. A three-stage solution algorithm is presented which can be applied to any nonlinear partial differential equation. Two generalized integral transforms were developed as the T-transform for the time domain and the B-transform for the spatial domain. The thermal diffusion describing function (TDDF) is developed for conduction of heat in solids and a general iterative solution along with convergence criteria is presented. The proposed solution method is used to solve the problem of heat transfer in nuclear fuel rods with annular fuel pellets. As a special instance the solid cylindrical fuel pellet is examined. A computer program is written which uses the describing function concept for computing fuel pin temperatures in the radial direction during reactor transients. The second problem investigated was the neutron diffusion equation which is intrinsically different from the first case. Although, for most situations, it can be treated as a linear differential equation, the describing function method is still applicable. A describing function solution is derived for two possible cases: constant diffusion coefficient and variable diffusion coefficient. Two classes of describing functions are defined for each case which portray the leakage and absorption phenomena. For the specific case of a slab reactor criticality problem the comparison between analytical and describing function solutions revealed an excellent agreement.
Some computational techniques for estimating human operator describing functions
NASA Technical Reports Server (NTRS)
Levison, W. H.
1986-01-01
Computational procedures for improving the reliability of human operator describing functions are described. Special attention is given to the estimation of standard errors associated with mean operator gain and phase shift as computed from an ensemble of experimental trials. This analysis pertains to experiments using sum-of-sines forcing functions. Both open-loop and closed-loop measurement environments are considered.
Continuous and discrete describing function analysis of the LST system
NASA Technical Reports Server (NTRS)
Kuo, B. C.; Singh, G.; Yackel, R. A.
1973-01-01
A describing function of the control moment gyros (CMG) frictional nonlinearity is derived using the analytic torque equation. Computer simulation of the simplified Large Space Telescope (LST) system with the analytic torque expression is discussed along with the transfer functions of the sampled-data LST system, and the discrete describing function of the GMC frictionality.
NASA Technical Reports Server (NTRS)
Yungster, Shaye; Radhakrishnan, Krishnan
1994-01-01
A new fully implicit, time accurate algorithm suitable for chemically reacting, viscous flows in the transonic-to-hypersonic regime is described. The method is based on a class of Total Variation Diminishing (TVD) schemes and uses successive Gauss-Siedel relaxation sweeps. The inversion of large matrices is avoided by partitioning the system into reacting and nonreacting parts, but still maintaining a fully coupled interaction. As a result, the matrices that have to be inverted are of the same size as those obtained with the commonly used point implicit methods. In this paper we illustrate the applicability of the new algorithm to hypervelocity unsteady combustion applications. We present a series of numerical simulations of the periodic combustion instabilities observed in ballistic-range experiments of blunt projectiles flying at subdetonative speeds through hydrogen-air mixtures. The computed frequencies of oscillation are in excellent agreement with experimental data.
Sinusoidal input describing function for hysteresis followed by elementary backlash
NASA Technical Reports Server (NTRS)
Ringland, R. F.
1976-01-01
The author proposes a new sinusoidal input describing function which accounts for the serial combination of hysteresis followed by elementary backlash in a single nonlinear element. The output of the hysteresis element drives the elementary backlash element. Various analytical forms of the describing function are given, depending on the a/A ratio, where a is the half width of the hysteresis band or backlash gap, and A is the amplitude of the assumed input sinusoid, and on the value of the parameter representing the fraction of a attributed to the backlash characteristic. The negative inverse describing function is plotted on a gain-phase plot, and it is seen that a relatively small amount of backlash leads to domination of the backlash character in the describing function. The extent of the region of the gain-phase plane covered by the describing function is such as to guarantee some form of limit cycle behavior in most closed-loop systems.
Accurate measurement of unsteady state fluid temperature
NASA Astrophysics Data System (ADS)
Jaremkiewicz, Magdalena
2016-07-01
In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different construction but with the same housing outer diameter equal to 15 mm. One of them is a K-type industrial thermometer widely available commercially. The temperature indicated by the thermometer was corrected considering the thermometers as the first or second order inertia devices. The new design of a thermometer was proposed and also used to measure the temperature of boiling water. Its characteristic feature is a cylinder-shaped housing with the sheath thermocouple located in its center. The temperature of the fluid was determined based on measurements taken in the axis of the solid cylindrical element (housing) using the inverse space marching method. Measurements of the transient temperature of the air flowing through the wind tunnel using the same thermometers were also carried out. The proposed measurement technique provides more accurate results compared with measurements using industrial thermometers in conjunction with simple temperature correction using the inertial thermometer model of the first or second order. By comparing the results, it was demonstrated that the new thermometer allows obtaining the fluid temperature much faster and with higher accuracy in comparison to the industrial thermometer. Accurate measurements of the fast changing fluid temperature are possible due to the low inertia thermometer and fast space marching method applied for solving the inverse heat conduction problem.
The first accurate description of an aurora
NASA Astrophysics Data System (ADS)
Schröder, Wilfried
2006-12-01
As technology has advanced, the scientific study of auroral phenomena has increased by leaps and bounds. A look back at the earliest descriptions of aurorae offers an interesting look into how medieval scholars viewed the subjects that we study.Although there are earlier fragmentary references in the literature, the first accurate description of the aurora borealis appears to be that published by the German Catholic scholar Konrad von Megenberg (1309-1374) in his book Das Buch der Natur (The Book of Nature). The book was written between 1349 and 1350.
Are Kohn-Sham conductances accurate?
Mera, H; Niquet, Y M
2010-11-19
We use Fermi-liquid relations to address the accuracy of conductances calculated from the single-particle states of exact Kohn-Sham (KS) density functional theory. We demonstrate a systematic failure of this procedure for the calculation of the conductance, and show how it originates from the lack of renormalization in the KS spectral function. In certain limits this failure can lead to a large overestimation of the true conductance. We also show, however, that the KS conductances can be accurate for single-channel molecular junctions and systems where direct Coulomb interactions are strongly dominant. PMID:21231333
Accurate density functional thermochemistry for larger molecules.
Raghavachari, K.; Stefanov, B. B.; Curtiss, L. A.; Lucent Tech.
1997-06-20
Density functional methods are combined with isodesmic bond separation reaction energies to yield accurate thermochemistry for larger molecules. Seven different density functionals are assessed for the evaluation of heats of formation, Delta H 0 (298 K), for a test set of 40 molecules composed of H, C, O and N. The use of bond separation energies results in a dramatic improvement in the accuracy of all the density functionals. The B3-LYP functional has the smallest mean absolute deviation from experiment (1.5 kcal mol/f).
New law requires 'medically accurate' lesson plans.
1999-09-17
The California Legislature has passed a bill requiring all textbooks and materials used to teach about AIDS be medically accurate and objective. Statements made within the curriculum must be supported by research conducted in compliance with scientific methods, and published in peer-reviewed journals. Some of the current lesson plans were found to contain scientifically unsupported and biased information. In addition, the bill requires material to be "free of racial, ethnic, or gender biases." The legislation is supported by a wide range of interests, but opposed by the California Right to Life Education Fund, because they believe it discredits abstinence-only material. PMID:11366835
Describing Willow Flycatcher habitats: scale perspectives and gender differences
Sedgwick, James A.; Knopf, Fritz L.
1992-01-01
We compared habitat characteristics of nest sites (female-selected sites) and song perch sites (male-selected sites) with those of sites unused by Willow Flycatchers (Empidonax traillii) at three different scales of vegetation measurement: (1) microplot (central willow [Salix spp.] bush and four adjacent bushes); (2) mesoplot (0.07 ha); and, (3) macroplot (flycatcher territory size). Willow Flycatchers exhibited vegetation preferences at all three scales. Nest sites were distinguished by high willow density and low variability in willow patch size and bush height. Song perch sites were characterized by large central shrubs, low central shrub vigor, and high variability in shrub size. Unused sites were characterized by greater distances between willows and willow patches, less willow coverage, and a smaller riparian zone width than either nest or song perch sites. At all scales, nest sites were situated farther from unused sites in multivariate habitat space than were song perch sites, suggesting (1) a correspondence among scales in their ability to describe Willow Flycatcher habitat, and (2) females are more discriminating in habitat selection than males. Microhabitat differences between male-selected (song perch) and female-selected (nest) sites were evident at the two smaller scales; at the finest scale, the segregation in habitat space between male-selected and female-selected sites was greater than that between male-selected and unused sites. Differences between song perch and nest sites were not apparent at the scale of flycatcher territory size, possibly due to inclusion of (1) both nest and song perch sites, (2) defended, but unused habitat, and/or (3) habitat outside of the territory, in larger scale analyses. The differences between nest and song perch sites at the finer scales reflect their different functions (e.g., nest concealment and microclimatic requirements vs. advertising and territorial defense, respectively), and suggest that the exclusive use
Enhanced ocean observational capability
Volpe, A M; Esser, B K
2000-01-10
Coastal oceans are vital to world health and sustenance. Technology that enables new observations has always been the driver of discovery in ocean sciences. In this context, we describe the first at sea deployment and operation of an inductively coupled plasma mass spectrometer (ICPMS) for continuous measurement of trace elements in seawater. The purpose of these experiments was to demonstrate that an ICPMS could be operated in a corrosive and high vibration environment with no degradation in performance. Significant advances occurred this past year due to ship time provided by Scripps Institution of Oceanography (UCSD), as well as that funded through this project. Evaluation at sea involved performance testing and characterization of several real-time seawater analysis modes. We show that mass spectrometers can rapidly, precisely and accurately determine ultratrace metal concentrations in seawater, thus allowing high-resolution mapping of large areas of surface seawater. This analytical capability represents a significant advance toward real-time observation and understanding of water mass chemistry in dynamic coastal environments. In addition, a joint LLNL-SIO workshop was convened to define and design new technologies for ocean observation. Finally, collaborative efforts were initiated with atmospheric scientists at LLNL to identify realistic coastal ocean and river simulation models to support real-time analysis and modeling of hazardous material releases in coastal waterways.
The FLUKA Code: An Accurate Simulation Tool for Particle Therapy
Battistoni, Giuseppe; Bauer, Julia; Boehlen, Till T.; Cerutti, Francesco; Chin, Mary P. W.; Dos Santos Augusto, Ricardo; Ferrari, Alfredo; Ortega, Pablo G.; Kozłowska, Wioletta; Magro, Giuseppe; Mairani, Andrea; Parodi, Katia; Sala, Paola R.; Schoofs, Philippe; Tessonnier, Thomas; Vlachoudis, Vasilis
2016-01-01
Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both 4He and 12C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth–dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features. PMID:27242956
The FLUKA Code: An Accurate Simulation Tool for Particle Therapy.
Battistoni, Giuseppe; Bauer, Julia; Boehlen, Till T; Cerutti, Francesco; Chin, Mary P W; Dos Santos Augusto, Ricardo; Ferrari, Alfredo; Ortega, Pablo G; Kozłowska, Wioletta; Magro, Giuseppe; Mairani, Andrea; Parodi, Katia; Sala, Paola R; Schoofs, Philippe; Tessonnier, Thomas; Vlachoudis, Vasilis
2016-01-01
Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both (4)He and (12)C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth-dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features. PMID:27242956
A spectrally accurate algorithm for electromagnetic scattering in three dimensions
NASA Astrophysics Data System (ADS)
Ganesh, M.; Hawkins, S.
2006-09-01
In this work we develop, implement and analyze a high-order spectrally accurate algorithm for computation of the echo area, and monostatic and bistatic radar cross-section (RCS) of a three dimensional perfectly conducting obstacle through simulation of the time-harmonic electromagnetic waves scattered by the conductor. Our scheme is based on a modified boundary integral formulation (of the Maxwell equations) that is tolerant to basis functions that are not tangential on the conductor surface. We test our algorithm with extensive computational experiments using a variety of three dimensional perfect conductors described in spherical coordinates, including benchmark radar targets such as the metallic NASA almond and ogive. The monostatic RCS measurements for non-convex conductors require hundreds of incident waves (boundary conditions). We demonstrate that the monostatic RCS of small (to medium) sized conductors can be computed using over one thousand incident waves within a few minutes (to a few hours) of CPU time. We compare our results with those obtained using method of moments based industrial standard three dimensional electromagnetic codes CARLOS, CICERO, FE-IE, FERM, and FISC. Finally, we prove the spectrally accurate convergence of our algorithm for computing the surface current, far-field, and RCS values of a class of conductors described globally in spherical coordinates.
Accurate basis set truncation for wavefunction embedding
NASA Astrophysics Data System (ADS)
Barnes, Taylor A.; Goodpaster, Jason D.; Manby, Frederick R.; Miller, Thomas F.
2013-07-01
Density functional theory (DFT) provides a formally exact framework for performing embedded subsystem electronic structure calculations, including DFT-in-DFT and wavefunction theory-in-DFT descriptions. In the interest of efficiency, it is desirable to truncate the atomic orbital basis set in which the subsystem calculation is performed, thus avoiding high-order scaling with respect to the size of the MO virtual space. In this study, we extend a recently introduced projection-based embedding method [F. R. Manby, M. Stella, J. D. Goodpaster, and T. F. Miller III, J. Chem. Theory Comput. 8, 2564 (2012)], 10.1021/ct300544e to allow for the systematic and accurate truncation of the embedded subsystem basis set. The approach is applied to both covalently and non-covalently bound test cases, including water clusters and polypeptide chains, and it is demonstrated that errors associated with basis set truncation are controllable to well within chemical accuracy. Furthermore, we show that this approach allows for switching between accurate projection-based embedding and DFT embedding with approximate kinetic energy (KE) functionals; in this sense, the approach provides a means of systematically improving upon the use of approximate KE functionals in DFT embedding.
Accurate radiative transfer calculations for layered media.
Selden, Adrian C
2016-07-01
Simple yet accurate results for radiative transfer in layered media with discontinuous refractive index are obtained by the method of K-integrals. These are certain weighted integrals applied to the angular intensity distribution at the refracting boundaries. The radiative intensity is expressed as the sum of the asymptotic angular intensity distribution valid in the depth of the scattering medium and a transient term valid near the boundary. Integrated boundary equations are obtained, yielding simple linear equations for the intensity coefficients, enabling the angular emission intensity and the diffuse reflectance (albedo) and transmittance of the scattering layer to be calculated without solving the radiative transfer equation directly. Examples are given of half-space, slab, interface, and double-layer calculations, and extensions to multilayer systems are indicated. The K-integral method is orders of magnitude more accurate than diffusion theory and can be applied to layered scattering media with a wide range of scattering albedos, with potential applications to biomedical and ocean optics. PMID:27409700
How Accurately can we Calculate Thermal Systems?
Cullen, D; Blomquist, R N; Dean, C; Heinrichs, D; Kalugin, M A; Lee, M; Lee, Y; MacFarlan, R; Nagaya, Y; Trkov, A
2004-04-20
I would like to determine how accurately a variety of neutron transport code packages (code and cross section libraries) can calculate simple integral parameters, such as K{sub eff}, for systems that are sensitive to thermal neutron scattering. Since we will only consider theoretical systems, we cannot really determine absolute accuracy compared to any real system. Therefore rather than accuracy, it would be more precise to say that I would like to determine the spread in answers that we obtain from a variety of code packages. This spread should serve as an excellent indicator of how accurately we can really model and calculate such systems today. Hopefully, eventually this will lead to improvements in both our codes and the thermal scattering models that they use in the future. In order to accomplish this I propose a number of extremely simple systems that involve thermal neutron scattering that can be easily modeled and calculated by a variety of neutron transport codes. These are theoretical systems designed to emphasize the effects of thermal scattering, since that is what we are interested in studying. I have attempted to keep these systems very simple, and yet at the same time they include most, if not all, of the important thermal scattering effects encountered in a large, water-moderated, uranium fueled thermal system, i.e., our typical thermal reactors.
Accurate shear measurement with faint sources
Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn
2015-01-01
For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.
Accurate pose estimation for forensic identification
NASA Astrophysics Data System (ADS)
Merckx, Gert; Hermans, Jeroen; Vandermeulen, Dirk
2010-04-01
In forensic authentication, one aims to identify the perpetrator among a series of suspects or distractors. A fundamental problem in any recognition system that aims for identification of subjects in a natural scene is the lack of constrains on viewing and imaging conditions. In forensic applications, identification proves even more challenging, since most surveillance footage is of abysmal quality. In this context, robust methods for pose estimation are paramount. In this paper we will therefore present a new pose estimation strategy for very low quality footage. Our approach uses 3D-2D registration of a textured 3D face model with the surveillance image to obtain accurate far field pose alignment. Starting from an inaccurate initial estimate, the technique uses novel similarity measures based on the monogenic signal to guide a pose optimization process. We will illustrate the descriptive strength of the introduced similarity measures by using them directly as a recognition metric. Through validation, using both real and synthetic surveillance footage, our pose estimation method is shown to be accurate, and robust to lighting changes and image degradation.
Accurate determination of characteristic relative permeability curves
NASA Astrophysics Data System (ADS)
Krause, Michael H.; Benson, Sally M.
2015-09-01
A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.
Describing Simple Data Access Services Version 1.0
NASA Astrophysics Data System (ADS)
Plante, Raymond; Delago, Jesus; Harrison, Paul; Tody, Doug; IVOA Registry Working Group; Plante, Raymond
2013-11-01
An application that queries or consumes descriptions of VO resources must be able to recognize a resource's support for standard IVOA protocols. This specification describes how to describe a service that supports any of the four fundamental data access protocols Simple Cone Search (SCS), Simple Image Access (SIA), Simple Spectral Access (SSA), Simple Line Access (SLA) using the VOResource XML encoding standard. A key part of this specification is the set of VOResource XML extension schemas that define new metadata that are specific to those protocols. This document describes in particular rules for describing such services within the context of IVOA Registries and data discovery as well as the VO Standard Interface (VOSI) and service selfdescription. In particular, this document spells out the essential markup needed to identify support for a standard protocol and the base URL required to access the interface that supports that protocol.
On three new Orchestina species (Araneae: Oonopidae) described from China.
Liu, Keke; Xiao, Yonghong; Xu, Xiang
2016-01-01
Three new species of oonopid spider from China are diagnosed, described and illustrated: Orchestina apiculata sp. nov. from Hunan, O. bialata sp. nov. and O. multipunctata sp. nov. from Jiangxi. The total number of the known species of Orchestina from China rises to 11 with the addition of three new species described in the present paper. Relationships with Asian and Afrotropical representatives are discussed. PMID:27395233
NASA Astrophysics Data System (ADS)
Fatoohi, L. J.
There are two main medieval Arab sources of astronomical observations: chronicles and astronomical treatises. Medieval Arabs produced numerous chronicles many of which reported astronomical events that the chroniclers themselves observed or were witnessed by others. Astronomical phenomena that were recorded by chroniclers include solar and lunar eclipses, cometary apparitions, meteors, and meteor showers. Muslim astronomers produced many astronomical treatises known as zijes. Zijes include records of mainly predictable phenomena, such as eclipses of the Sun and Moon. Unlike chronicles, zijes usually ignore irregular phenomena such as the apparitions of comets and meteors, and meteor showers. Some zijes include astronomical observations, especially of eclipses. Not unexpectedly, records in zijes are in general more accurate than their counterparts in chronicles. However, research has shown that medieval Arab chronicles and zijes both contain some valuable astronomical observational data. Unfortunately, much of the heritage of medieval Arab chroniclers and astronomers is still in manuscript form. Moreover, most of the huge numbers of Arabic manuscripts that exist in various libraries, especially in Arab countries, are still uncatalogued. Until now there is only one catalogue of zijes which was compiled in the fifties and which includes brief comments on 200 zijes. There is a real need for systematic investigation of medieval Arab historical and astronomical manuscripts which exist in many libraries all over the world.
Describing function method applied to solution of nonlinear heat conduction equation
Nassersharif, B. )
1989-08-01
Describing functions have traditionally been used to obtain the solutions of systems of ordinary differential equations. The describing function concept has been extended to include the non-linear, distributed parameter solid heat conduction equation. A four-step solution algorithm is presented that may be applicable to many classes of nonlinear partial differential equations. As a specific application of the solution technique, the one-dimensional nonlinear transient heat conduction equation in an annular fuel pin is considered. A computer program was written to calculate one-dimensional transient heat conduction in annular cylindrical geometry. It is found that the quasi-linearization used in the describing function method is as accurate as and faster than true linearization methods.
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Arnold, James O. (Technical Monitor)
1996-01-01
The vibrational frequencies and infrared intensities of naphthalene neutral and cation are studied at the self-consistent-field (SCF), second-order Moller-Plesset (MP2), and density functional theory (DFT) levels using a variety of one-particle basis sets. Very accurate frequencies can be obtained at the DFT level in conjunction with large basis sets if they are scaled with two factors, one for the C-H stretches and a second for all other modes. We also find remarkably good agreement at the B3LYP/4-31G level using only one scale factor. Unlike the neutral PAHs where all methods do reasonably well for the intensities, only the DFT results are accurate for the PAH cations. The failure of the SCF and MP2 methods is caused by symmetry breaking and an inability to describe charge delocalization. We present several interesting cases of symmetry breaking in this study. An assessment is made as to whether an ensemble of PAH neutrals or cations could account for the unidentified infrared bands observed in many astronomical sources.
Accurate Transposable Element Annotation Is Vital When Analyzing New Genome Assemblies
Platt, Roy N.; Blanco-Berdugo, Laura; Ray, David A.
2016-01-01
Transposable elements (TEs) are mobile genetic elements with the ability to replicate themselves throughout the host genome. In some taxa TEs reach copy numbers in hundreds of thousands and can occupy more than half of the genome. The increasing number of reference genomes from nonmodel species has begun to outpace efforts to identify and annotate TE content and methods that are used vary significantly between projects. Here, we demonstrate variation that arises in TE annotations when less than optimal methods are used. We found that across a variety of taxa, the ability to accurately identify TEs based solely on homology decreased as the phylogenetic distance between the queried genome and a reference increased. Next we annotated repeats using homology alone, as is often the case in new genome analyses, and a combination of homology and de novo methods as well as an additional manual curation step. Reannotation using these methods identified a substantial number of new TE subfamilies in previously characterized genomes, recognized a higher proportion of the genome as repetitive, and decreased the average genetic distance within TE families, implying recent TE accumulation. Finally, these finding—increased recognition of younger TEs—were confirmed via an analysis of the postman butterfly (Heliconius melpomene). These observations imply that complete TE annotation relies on a combination of homology and de novo–based repeat identification, manual curation, and classification and that relying on simple, homology-based methods is insufficient to accurately describe the TE landscape of a newly sequenced genome. PMID:26802115
Evaluation of equations for describing the human crystalline lens
NASA Astrophysics Data System (ADS)
Giovanzana, Stefano; Schachar, Ronald A.; Talu, Stefan; Kirby, Roger D.; Yan, Eric; Pierscionek, Barbara K.
2013-03-01
Accurate mathematical descriptions of the human crystalline lens surface shape are required to properly understand the nature of functional adaptations that occur when the lens shape alters to changes in refractive power. Using least squares method, the total mean normal distance, smoothness, rate of change of the transverse and sagittal radii of curvatures and continuity at the lens equator between eight mathematical functions: conic, figuring conicoid, generalized conic, Hermans conic patch, Urs polynomial, Urs 10th order Fourier series, Chien, and Giovanzana, and 17 human crystalline lenses were evaluated. The mean differences of the fits of all the equations to the whole lens and to the central 8 mm of the lens surfaces were >24 μm with comparable standard deviations. When considering fit smoothness and continuity at the equator, the Giovanzana and Chien functions are most representative of the lens surface.
Accurate ab initio Quartic Force Fields of Cyclic and Bent HC2N Isomers
NASA Technical Reports Server (NTRS)
Inostroza, Natalia; Huang, Xinchuan; Lee, Timothy J.
2012-01-01
Highly correlated ab initio quartic force field (QFFs) are used to calculate the equilibrium structures and predict the spectroscopic parameters of three HC2N isomers. Specifically, the ground state quasilinear triplet and the lowest cyclic and bent singlet isomers are included in the present study. Extensive treatment of correlation effects were included using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T). Dunning s correlation-consistent basis sets cc-pVXZ, X=3,4,5, were used, and a three-point formula for extrapolation to the one-particle basis set limit was used. Core-correlation and scalar relativistic corrections were also included to yield highly accurate QFFs. The QFFs were used together with second-order perturbation theory (with proper treatment of Fermi resonances) and variational methods to solve the nuclear Schr dinger equation. The quasilinear nature of the triplet isomer is problematic, and it is concluded that a QFF is not adequate to describe properly all of the fundamental vibrational frequencies and spectroscopic constants (though some constants not dependent on the bending motion are well reproduced by perturbation theory). On the other hand, this procedure (a QFF together with either perturbation theory or variational methods) leads to highly accurate fundamental vibrational frequencies and spectroscopic constants for the cyclic and bent singlet isomers of HC2N. All three isomers possess significant dipole moments, 3.05D, 3.06D, and 1.71D, for the quasilinear triplet, the cyclic singlet, and the bent singlet isomers, respectively. It is concluded that the spectroscopic constants determined for the cyclic and bent singlet isomers are the most accurate available, and it is hoped that these will be useful in the interpretation of high-resolution astronomical observations or laboratory experiments.
Accurate Thermal Stresses for Beams: Normal Stress
NASA Technical Reports Server (NTRS)
Johnson, Theodore F.; Pilkey, Walter D.
2003-01-01
Formulations for a general theory of thermoelasticity to generate accurate thermal stresses for structural members of aeronautical vehicles were developed in 1954 by Boley. The formulation also provides three normal stresses and a shear stress along the entire length of the beam. The Poisson effect of the lateral and transverse normal stresses on a thermally loaded beam is taken into account in this theory by employing an Airy stress function. The Airy stress function enables the reduction of the three-dimensional thermal stress problem to a two-dimensional one. Numerical results from the general theory of thermoelasticity are compared to those obtained from strength of materials. It is concluded that the theory of thermoelasticity for prismatic beams proposed in this paper can be used instead of strength of materials when precise stress results are desired.
Accurate Thermal Stresses for Beams: Normal Stress
NASA Technical Reports Server (NTRS)
Johnson, Theodore F.; Pilkey, Walter D.
2002-01-01
Formulations for a general theory of thermoelasticity to generate accurate thermal stresses for structural members of aeronautical vehicles were developed in 1954 by Boley. The formulation also provides three normal stresses and a shear stress along the entire length of the beam. The Poisson effect of the lateral and transverse normal stresses on a thermally loaded beam is taken into account in this theory by employing an Airy stress function. The Airy stress function enables the reduction of the three-dimensional thermal stress problem to a two-dimensional one. Numerical results from the general theory of thermoelasticity are compared to those obtained from strength of materials. It is concluded that the theory of thermoelasticity for prismatic beams proposed in this paper can be used instead of strength of materials when precise stress results are desired.
Highly accurate articulated coordinate measuring machine
Bieg, Lothar F.; Jokiel, Jr., Bernhard; Ensz, Mark T.; Watson, Robert D.
2003-12-30
Disclosed is a highly accurate articulated coordinate measuring machine, comprising a revolute joint, comprising a circular encoder wheel, having an axis of rotation; a plurality of marks disposed around at least a portion of the circumference of the encoder wheel; bearing means for supporting the encoder wheel, while permitting free rotation of the encoder wheel about the wheel's axis of rotation; and a sensor, rigidly attached to the bearing means, for detecting the motion of at least some of the marks as the encoder wheel rotates; a probe arm, having a proximal end rigidly attached to the encoder wheel, and having a distal end with a probe tip attached thereto; and coordinate processing means, operatively connected to the sensor, for converting the output of the sensor into a set of cylindrical coordinates representing the position of the probe tip relative to a reference cylindrical coordinate system.
Practical aspects of spatially high accurate methods
NASA Technical Reports Server (NTRS)
Godfrey, Andrew G.; Mitchell, Curtis R.; Walters, Robert W.
1992-01-01
The computational qualities of high order spatially accurate methods for the finite volume solution of the Euler equations are presented. Two dimensional essentially non-oscillatory (ENO), k-exact, and 'dimension by dimension' ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy, computational cost and oscillatory behavior in supersonic flows with shocks. Inherent steady state convergence difficulties are demonstrated for adaptive stencil algorithms. An exact solution to the heat equation is used to determine reconstruction error, and the computational intensity is reflected in operation counts. Standard MUSCL differencing is included for comparison. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock reflection problem. A vortex-shock interaction demonstrates the ability of the ENO scheme to excel in simulating unsteady high-frequency flow physics.
The thermodynamic cost of accurate sensory adaptation
NASA Astrophysics Data System (ADS)
Tu, Yuhai
2015-03-01
Living organisms need to obtain and process environment information accurately in order to make decisions critical for their survival. Much progress have been made in identifying key components responsible for various biological functions, however, major challenges remain to understand system-level behaviors from the molecular-level knowledge of biology and to unravel possible physical principles for the underlying biochemical circuits. In this talk, we will present some recent works in understanding the chemical sensory system of E. coli by combining theoretical approaches with quantitative experiments. We focus on addressing the questions on how cells process chemical information and adapt to varying environment, and what are the thermodynamic limits of key regulatory functions, such as adaptation.
Accurate numerical solutions of conservative nonlinear oscillators
NASA Astrophysics Data System (ADS)
Khan, Najeeb Alam; Nasir Uddin, Khan; Nadeem Alam, Khan
2014-12-01
The objective of this paper is to present an investigation to analyze the vibration of a conservative nonlinear oscillator in the form u" + lambda u + u^(2n-1) + (1 + epsilon^2 u^(4m))^(1/2) = 0 for any arbitrary power of n and m. This method converts the differential equation to sets of algebraic equations and solve numerically. We have presented for three different cases: a higher order Duffing equation, an equation with irrational restoring force and a plasma physics equation. It is also found that the method is valid for any arbitrary order of n and m. Comparisons have been made with the results found in the literature the method gives accurate results.
Accurate metacognition for visual sensory memory representations.
Vandenbroucke, Annelinde R E; Sligte, Ilja G; Barrett, Adam B; Seth, Anil K; Fahrenfort, Johannes J; Lamme, Victor A F
2014-04-01
The capacity to attend to multiple objects in the visual field is limited. However, introspectively, people feel that they see the whole visual world at once. Some scholars suggest that this introspective feeling is based on short-lived sensory memory representations, whereas others argue that the feeling of seeing more than can be attended to is illusory. Here, we investigated this phenomenon by combining objective memory performance with subjective confidence ratings during a change-detection task. This allowed us to compute a measure of metacognition--the degree of knowledge that subjects have about the correctness of their decisions--for different stages of memory. We show that subjects store more objects in sensory memory than they can attend to but, at the same time, have similar metacognition for sensory memory and working memory representations. This suggests that these subjective impressions are not an illusion but accurate reflections of the richness of visual perception. PMID:24549293
Apparatus for accurately measuring high temperatures
Smith, Douglas D.
1985-01-01
The present invention is a thermometer used for measuring furnace temperaes in the range of about 1800.degree. to 2700.degree. C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.
Apparatus for accurately measuring high temperatures
Smith, D.D.
The present invention is a thermometer used for measuring furnace temperatures in the range of about 1800/sup 0/ to 2700/sup 0/C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.
Toward Accurate and Quantitative Comparative Metagenomics.
Nayfach, Stephen; Pollard, Katherine S
2016-08-25
Shotgun metagenomics and computational analysis are used to compare the taxonomic and functional profiles of microbial communities. Leveraging this approach to understand roles of microbes in human biology and other environments requires quantitative data summaries whose values are comparable across samples and studies. Comparability is currently hampered by the use of abundance statistics that do not estimate a meaningful parameter of the microbial community and biases introduced by experimental protocols and data-cleaning approaches. Addressing these challenges, along with improving study design, data access, metadata standardization, and analysis tools, will enable accurate comparative metagenomics. We envision a future in which microbiome studies are replicable and new metagenomes are easily and rapidly integrated with existing data. Only then can the potential of metagenomics for predictive ecological modeling, well-powered association studies, and effective microbiome medicine be fully realized. PMID:27565341
The importance of accurate atmospheric modeling
NASA Astrophysics Data System (ADS)
Payne, Dylan; Schroeder, John; Liang, Pang
2014-11-01
This paper will focus on the effect of atmospheric conditions on EO sensor performance using computer models. We have shown the importance of accurately modeling atmospheric effects for predicting the performance of an EO sensor. A simple example will demonstrated how real conditions for several sites in China will significantly impact on image correction, hyperspectral imaging, and remote sensing. The current state-of-the-art model for computing atmospheric transmission and radiance is, MODTRAN® 5, developed by the US Air Force Research Laboratory and Spectral Science, Inc. Research by the US Air Force, Navy and Army resulted in the public release of LOWTRAN 2 in the early 1970's. Subsequent releases of LOWTRAN and MODTRAN® have continued until the present. Please verify that (1) all pages are present, (2) all figures are correct, (3) all fonts and special characters are correct, and (4) all text and figures fit within the red margin lines shown on this review document. Complete formatting information is available at http://SPIE.org/manuscripts Return to the Manage Active Submissions page at http://spie.org/submissions/tasks.aspx and approve or disapprove this submission. Your manuscript will not be published without this approval. Please contact author_help@spie.org with any questions or concerns. The paper will demonstrate the importance of using validated models and local measured meteorological, atmospheric and aerosol conditions to accurately simulate the atmospheric transmission and radiance. Frequently default conditions are used which can produce errors of as much as 75% in these values. This can have significant impact on remote sensing applications.
The high cost of accurate knowledge.
Sutcliffe, Kathleen M; Weber, Klaus
2003-05-01
Many business thinkers believe it's the role of senior managers to scan the external environment to monitor contingencies and constraints, and to use that precise knowledge to modify the company's strategy and design. As these thinkers see it, managers need accurate and abundant information to carry out that role. According to that logic, it makes sense to invest heavily in systems for collecting and organizing competitive information. Another school of pundits contends that, since today's complex information often isn't precise anyway, it's not worth going overboard with such investments. In other words, it's not the accuracy and abundance of information that should matter most to top executives--rather, it's how that information is interpreted. After all, the role of senior managers isn't just to make decisions; it's to set direction and motivate others in the face of ambiguities and conflicting demands. Top executives must interpret information and communicate those interpretations--they must manage meaning more than they must manage information. So which of these competing views is the right one? Research conducted by academics Sutcliffe and Weber found that how accurate senior executives are about their competitive environments is indeed less important for strategy and corresponding organizational changes than the way in which they interpret information about their environments. Investments in shaping those interpretations, therefore, may create a more durable competitive advantage than investments in obtaining and organizing more information. And what kinds of interpretations are most closely linked with high performance? Their research suggests that high performers respond positively to opportunities, yet they aren't overconfident in their abilities to take advantage of those opportunities. PMID:12747164
Describing small-scale structure in random media using pulse-echo ultrasound
Insana, Michael F.; Wagner, Robert F.; Brown, David G.; Hall, Timothy J.
2009-01-01
A method for estimating structural properties of random media is described. The size, number density, and scattering strength of particles are estimated from an analysis of the radio frequency (rf) echo signal power spectrum. Simple correlation functions and the accurate scattering theory of Faran [J. J. Faran, J. Acoust. Soc. Am. 23, 405–418 (1951)], which includes the effects of shear waves, were used separately to model backscatter from spherical particles and thereby describe the structures of the medium. These methods were tested using both glass sphere-in-agar and polystyrene sphere-in-agar scattering media. With the appropriate correlation function, it was possible to measure glass sphere diameters with an accuracy of 20%. It was not possible to accurately estimate the size of polystyrene spheres with the simple spherical and Gaussian correlation models examined because of a significant shear wave contribution. Using the Faran scattering theory for spheres, however, the accuracy for estimating diameters was improved to 10% for both glass and polystyrene scattering media. It was possible to estimate the product of the average scattering particle number density and the average scattering strength per particle, but with lower accuracy than the size estimates. The dependence of the measurement accuracy on the inclusion of shear waves, the wavelength of sound, and medium attenuation are considered, and the implications for describing the structure of biological soft tissues are discussed. PMID:2299033
Using Neural Networks to Describe Complex Phase Transformation Behavior
Vitek, J.M.; David, S.A.
1999-05-24
Final microstructures can often be the end result of a complex sequence of phase transformations. Fundamental analyses may be used to model various stages of the overall behavior but they are often impractical or cumbersome when considering multicomponent systems covering a wide range of compositions. Neural network analysis may be a useful alternative method of identifying and describing phase transformation beavior. A neural network model for ferrite prediction in stainless steel welds is described. It is shown that the neural network analysis provides valuable information that accounts for alloying element interactions. It is suggested that neural network analysis may be extremely useful for analysis when more fundamental approaches are unavailable or overly burdensome.
Model framework for describing the dynamics of evolving networks
NASA Astrophysics Data System (ADS)
Tobochnik, Jan; Strandburg, Katherine; Csardi, Gabor; Erdi, Peter
2007-03-01
We present a model framework for describing the dynamics of evolving networks. In this framework the addition of edges is stochastically governed by some important intrinsic and structural properties of network vertices through an attractiveness function. We discuss the solution of the inverse problem: determining the attractiveness function from the network evolution data. We also present a number of example applications: the description of the US patent citation network using vertex degree, patent age and patent category variables, and we show how the time-dependent version of the method can be used to find and describe important changes in the internal dynamics. We also compare our results to scientific citation networks.
Stability of interconnected dynamical systems described on Banach spaces
NASA Technical Reports Server (NTRS)
Rasmussen, R. D.; Michel, A. N.
1976-01-01
New stability results for a large class of interconnected dynamical systems (also called composite systems or large scale systems) described on Banach spaces are established. In the present approach, the objective is always the same: to analyze large scale systems in terms of their lower order and simpler subsystems and in terms of their interconnecting structure. The present results provide a systematic procedure of analyzing hybrid dynamical systems (i.e., systems that are described by a mixture of different types of equations). To demonstrate the method of analysis advanced, two specific examples are considered.
NASA Astrophysics Data System (ADS)
Zhao, Xiao-mei; Xie, Dong-fan; Li, Qi
2015-02-01
With the development of intelligent transport system, advanced information feedback strategies have been developed to reduce traffic congestion and enhance the capacity. However, previous strategies provide accurate information to travelers and our simulation results show that accurate information brings negative effects, especially in delay case. Because travelers prefer to the best condition route with accurate information, and delayed information cannot reflect current traffic condition but past. Then travelers make wrong routing decisions, causing the decrease of the capacity and the increase of oscillations and the system deviating from the equilibrium. To avoid the negative effect, bounded rationality is taken into account by introducing a boundedly rational threshold BR. When difference between two routes is less than the BR, routes have equal probability to be chosen. The bounded rationality is helpful to improve the efficiency in terms of capacity, oscillation and the gap deviating from the system equilibrium.
NASA Technical Reports Server (NTRS)
Mueller, A. C.
1977-01-01
An analytical first order solution has been developed which describes the motion of an artificial satellite perturbed by an arbitrary number of zonal harmonics of the geopotential. A set of recursive relations for the solution, which was deduced from recursive relations of the geopotential, was derived. The method of solution is based on Von-Zeipel's technique applied to a canonical set of two-body elements in the extended phase space which incorporates the true anomaly as a canonical element. The elements are of Poincare type, that is, they are regular for vanishing eccentricities and inclinations. Numerical results show that this solution is accurate to within a few meters after 500 revolutions.
Accurate tremor locations from coherent S and P waves
NASA Astrophysics Data System (ADS)
Armbruster, John G.; Kim, Won-Young; Rubin, Allan M.
2014-06-01
Nonvolcanic tremor is an important component of the slow slip processes which load faults from below, but accurately locating tremor has proven difficult because tremor rarely contains clear P or S wave arrivals. Here we report the observation of coherence in the shear and compressional waves of tremor at widely separated stations which allows us to detect and accurately locate tremor events. An event detector using data from two stations sees the onset of tremor activity in the Cascadia tremor episodes of February 2003, July 2004, and September 2005 and confirms the previously reported south to north migration of the tremor. Event detectors using data from three and four stations give Sand P arrival times of high accuracy. The hypocenters of the tremor events fall at depths of ˜30 to ˜40 km and define a narrow plane dipping at a shallow angle to the northeast, consistent with the subducting plate interface. The S wave polarizations and P wave first motions define a source mechanism in agreement with the northeast convergence seen in geodetic observations of slow slip. Tens of thousands of locations determined by constraining the events to the plate interface show tremor sources highly clustered in space with a strongly similar pattern of sources in the three episodes examined. The deeper sources generate tremor in minor episodes as well. The extent to which the narrow bands of tremor sources overlap between the three major episodes suggests relative epicentral location errors as small as 1-2 km.
NASA Technical Reports Server (NTRS)
Graves, R. A., Jr.
1975-01-01
The previously obtained second-order-accurate partial implicitization numerical technique used in the solution of fluid dynamic problems was modified with little complication to achieve fourth-order accuracy. The Von Neumann stability analysis demonstrated the unconditional linear stability of the technique. The order of the truncation error was deduced from the Taylor series expansions of the linearized difference equations and was verified by numerical solutions to Burger's equation. For comparison, results were also obtained for Burger's equation using a second-order-accurate partial-implicitization scheme, as well as the fourth-order scheme of Kreiss.
THE FIRST ACCURATE PARALLAX DISTANCE TO A BLACK HOLE
Miller-Jones, J. C. A.; Jonker, P. G.; Dhawan, V.; Brisken, W.; Rupen, M. P.; Nelemans, G.; Gallo, E.
2009-12-01
Using astrometric VLBI observations, we have determined the parallax of the black hole X-ray binary V404 Cyg to be 0.418 +- 0.024 mas, corresponding to a distance of 2.39 +- 0.14 kpc, significantly lower than the previously accepted value. This model-independent estimate is the most accurate distance to a Galactic stellar-mass black hole measured to date. With this new distance, we confirm that the source was not super-Eddington during its 1989 outburst. The fitted distance and proper motion imply that the black hole in this system likely formed in a supernova, with the peculiar velocity being consistent with a recoil (Blaauw) kick. The size of the quiescent jets inferred to exist in this system is <1.4 AU at 22 GHz. Astrometric observations of a larger sample of such systems would provide useful insights into the formation and properties of accreting stellar-mass black holes.
College Students' Judgment of Others Based on Described Eating Pattern
ERIC Educational Resources Information Center
Pearson, Rebecca; Young, Michael
2008-01-01
Background: The literature available on attitudes toward eating patterns and people choosing various foods suggests the possible importance of "moral" judgments and desirable personality characteristics associated with the described eating patterns. Purpose: This study was designed to replicate and extend a 1993 study of college students'…
Method for describing fractures in subterranean earth formations
Shuck, Lowell Z.
1977-01-01
The configuration and directional orientation of natural or induced fractures in subterranean earth formations are described by introducing a liquid explosive into the fracture, detonating the explosive, and then monitoring the resulting acoustic emissions with strategically placed acoustic sensors as the explosion propagates through the fracture at a known rate.
25. VIEW LOOKING EAST THROUGH 'TUNNEL' DESCRIBED ABOVE. RAILCAR LOADING ...
25. VIEW LOOKING EAST THROUGH 'TUNNEL' DESCRIBED ABOVE. RAILCAR LOADING TUBES AT TOP FOREGROUND, SPERRY CORN ELEVATOR COMPLEX AT RIGHT AND ADJOINING WAREHOUSE AT LEFT - Sperry Corn Elevator Complex, Weber Avenue (North side), West of Edison Street, Stockton, San Joaquin County, CA
Describing an "Effective" Principal: Perceptions of the Central Office Leaders
ERIC Educational Resources Information Center
Parylo, Oksana; Zepeda, Sally J.
2014-01-01
The purpose of this qualitative study was to examine how district leaders of two school systems in the USA describe an effective principal. Membership categorisation analysis revealed that district leaders believed an effective principal had four major categories of characteristics: (1) documented characteristics (having a track record and being a…
New North American Chrysauginae (Pyralidae) described by Cashatt (1968)
Technology Transfer Automated Retrieval System (TEKTRAN)
The dissertation entitled “Revision of the Chrysauginae of North America” included new taxa that were never published and do not meet the requirements for availability by the International Code of Nomenclature. Therefore, the following taxa from this dissertation are described and illustrated: Arta ...
A General Problem Describer for Computer Assisted Instruction.
ERIC Educational Resources Information Center
Wools, Ronald Joe
Currently in computer-assisted instruction (CAI) systems a number of problems are presented to each student during a session, with each individual problem being specified by the author of the session. A better approach might be to provide the author with a language in which he can describe to the computer the general type of problem he wants his…
23. FISH CONVEYOR Conveyor described in Photo No. 21. A ...
23. FISH CONVEYOR Conveyor described in Photo No. 21. A portion of a second conveyor is seen on the left. Vertical post knocked askew and cracked cement base of the conveyor, attest to the condition of the building. - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA
Learning Communities and Community Development: Describing the Process.
ERIC Educational Resources Information Center
Moore, Allen B.; Brooks, Rusty
2000-01-01
Describes features of learning communities: they transform themselves, share wisdom and recognition, bring others in, and share results. Provides the case example of the Upper Savannah River Economic Coalition. Discusses actions of learning communities, barriers to their development, and future potential. (SK)
Tools for describing the reference architecture for space data systems
NASA Technical Reports Server (NTRS)
Shames, Peter; Yamada, Takahiro
2004-01-01
This paper has briefly presented the Reference Architecture for Space Data Systems (RASDS) that is being developed by the CCSDS Systems Architecture Working Group (SAWG). The SAWG generated some sample architectures (spacecraft onboard architectures, space link architectures, cross-support architectures) using this RASDS approach, and RASDS was proven to be a powerful tool for describing and relating different space data system architectures.
An Evolving Framework for Describing Student Engagement in Classroom Activities
ERIC Educational Resources Information Center
Azevedo, Flavio S.; diSessa, Andrea A.; Sherin, Bruce L.
2012-01-01
Student engagement in classroom activities is usually described as a function of factors such as human needs, affect, intention, motivation, interests, identity, and others. We take a different approach and develop a framework that models classroom engagement as a function of students' "conceptual competence" in the "specific content" (e.g., the…
Describing Elementary Teachers' Operative Systems: A Case Study
ERIC Educational Resources Information Center
Dotger, Sharon; McQuitty, Vicki
2014-01-01
This case study introduces the notion of an operative system to describe elementary teachers' knowledge and practice. Drawing from complex systems theory, the operative system is defined as the network of knowledge and practices that constituted teachers' work within a lesson study cycle. Data were gathered throughout a lesson study…
Describing Soils: Calibration Tool for Teaching Soil Rupture Resistance
ERIC Educational Resources Information Center
Seybold, C. A.; Harms, D. S.; Grossman, R. B.
2009-01-01
Rupture resistance is a measure of the strength of a soil to withstand an applied stress or resist deformation. In soil survey, during routine soil descriptions, rupture resistance is described for each horizon or layer in the soil profile. The lower portion of the rupture resistance classes are assigned based on rupture between thumb and…