Triple Charge Division (TCD) centroid finding method that uses modified pattern of Backgammon Shape Cathode (MBSC) is introduced for medium range length position sensitive detectors with optimum numbers of cathode segments. MBSC pattern has three separated areas and uses saw tooth like insulator gaps for separating the areas. Side areas of the MBSC pattern are severed by a central common area. Size of the central area is twice of the size of both sides. Whereas central area is the widest area among three, both sides` areas have the main role in position sensing. With the same resolution and linearity, active region of original Backgammon pattern increases twice by using MBSC pattern, and with the same length, linearity of TCD centroid finding is much better than Backgammon charge division readout method. Linearity prediction of TCD centroid finding and experimental results conducted us to find an optimum truncation of the apices of MBCS pattern in the central area. The TCD centroid finding has an especial readout method since charges must be collected from two segments in both sides and from three segments in the central area of MBSC pattern. The so called Graded Charge Division (GCD) is the especial readout method for TCD. The GCD readout is a combination of the charge division readout and sequence grading of serial segments. Position sensing with TCD centroid finding and GCD readout were done by two sizes MBSC patterns (200mm and 80mm) and Spatial resolution about 1% of the detector length is achieved.

Lifetimes of members of the superdeformed band in {sup 135}Nd have been determined by a Doppler-shift attenuation method. In this case, where side feeding occurs along the entire length of the cascade, centroid analysis does not give a unique answer and line-shape analysis is necessary. We find a transition quadrupole moment of 7.4{plus minus}1.0 b, corresponding to an axis ratio of 1.42. The side feeding is {similar to}4 times slower than the main cascade.

A new method for spike sorting of tetrode recordings during data acquisition is introduced. For each tetrode channel, putative spikes are detected by means of a threshold, and then convolved with a cascade of wavelet filters. These transformed putative spikes are averaged and this average is used as a matched filter to find portions of signals that are likely to contain a spike. A collection of vectors containing the correlation coefficients between putative spikes and the matched filters is then clustered using K-Means. Centroids of the resulting clusters contain enough information to sort spikes recorded by all tetrode channels simultaneously. On-line sorting is achieved by measuring euclidean distance between putative new spikes and the cluster centroids. PMID:21096737

Rachel Akeson. NASA Exoplanet Science Institute ... Exoplanet Database) to a new service, the “NASA Exoplanet Archive”. – Focus on ... Includes in/out of transit centroiding information. – Kepler light ... Method for users to identify candidates ...

The equation of motion for the centroid of globally coupled oscillators with natural frequency mismatch is obtained through a series expansion in order parameters, valid for any population size. In the case of strong coupling and narrow-frequency distribution the first-order expansion (corresponding to a system where the centroid is coupled to a second macroscopic variable), predicts transient and asymptotic properties of the dynamics of the centroid. Phase transitions appear as macroscopic bifurcations. Collective properties arising in the transient, and particularly critical perturbations, suggest a method of experimental relevance for identifying the parameters of the population.

Recently, we have applied the analytic continuation averaged spectrum method (ASM) to calculate collective density fluctuations in quantum liquid [27]. Unlike the maximum entropy (MaxEnt) method, the ASM approach is capable of revealing resolved modes in the dynamic structure factor in agreement with experiments. In this work we further develop the ASM to study single-particle dynamics in quantum liquids with dynamical susceptibilities that are characterized by a smooth spectrum. Surprisingly, we find that for the power spectrum of the velocity autocorrelation function there are pronounced differences in comparison with the MaxEnt approach, even for this simple case of smooth unimodal dynamic response. We show that for liquid para-hydrogen the ASM is closer to the centroid molecular dynami...

Spectral centroid estimation from backscattered ultrasound RF signals is the preliminary step for quantitative ultrasound analysis in many medical applications. The traditional approach of estimating the spectral centroid in the frequency domain takes a long time because discrete Fourier transform (DFT) processing for each RF segment is required. To avoid this, we propose time-domain methods to estimate the spectral centroid in this paper. First, we derive the continuous-time-domain equations for the spectral centroid estimation using Parseval's theorem and Hilbert transform theory. Then, we extend the method to the discrete-time domain to ease the implementation while maintaining the same accuracy as the calculation in the frequency domain. From the result, we observe that it is not practical to apply the discrete-time equations directly, because a high sampling rate is needed to approximate the time derivative in the discrete-time domain. Therefore, we also derive the feasible version of the discrete-time equations using a circular autocorrelation function, which has no constraints on the sampling rate for real RF signals acquired from pulse-echo ultrasound systems. Simulation results using numerical phantoms show that the time-domain calculation is approximately 4.4 times faster on average than the frequency-domain method when the software's built-in functions were used. The average estimation error compared with that of the frequency-domain method using DFT is less than 0.2% for the entire propagation depths. The proposed time-domain approach to estimate the spectral centroid can be easily implemented in real-time ultrasound systems. PMID:22711414

Text classification/categorization (TC) is to assign new unlabeled natural language documents to the predefined thematic categories. Centroid-based classifier (CC) has been widely used for TC because of its simplicity and efficiency. However, it has also been long criticized for its relatively low classification accuracy compared with state-of-the-art classifiers such as support vector machines (SVMs). In this paper, we find that for CC using only border instances rather than all instances to construct centroid vectors can obtain higher generalization accuracy. Along this line, we propose Border-Instance-based Iteratively Adjusted Centroid Classifier (IACC_BI), which relies on the border instances found by some routines, e.g. 1-Nearest-and-1-Furthest-Neighbors strategy, to construct centro...

Registration of medical images to each other and to physical space for the purposes of surgical planning and surgical navigation can be accomplished using externally attached fiducial markers. The accuracy of fiducial localization, that is, the accuracy of estimating the position of the marker's centroid, is extremely important because marker- based registration accuracy is proportional to localization accuracy. The traditional method of calculating the marker centroid using intensity weighting contains a serious logic flaw. This paper introduces a novel and efficient method for correcting this flaw. Theoretical analysis, computer simulation, and analysis of clinical images demonstrate the importance of this correction.

Purpose: To evaluate the use of megavoltage cone-beam computed tomography (MV CBCT) to measure interfractional variation in lung tumor position.Methods and Materials: Eight non–small-cell lung cancer patients participated in the study, 4 with respiratory gating and 4 without. All patients underwent MV CBCT scanning at weekly intervals. Contoured planning CT and MV CBCT images were spatially registered based on vertebral anatomy, and displacements of the tumor centroid determined. Setup error was assessed by comparing weekly portal orthogonal radiographs with digitally reconstructed radiographs generated from planning CT images. Hypothesis testing was performed to test the statistical significance of the volume difference, centroid displacement, and setup uncertainty.Results: The ver...

We present an in-depth statistical survey of flare heights of all X-ray microflares as observed by RHESSI between March 2002 and March 2007, a total of >25,000 events, an order of magnitude larger then previous studies. The microflares were found using a new flare-finding algorithm designed to search the 6-- 12~keV count-rate when RHESSI's full sensitivity was available in order to find the smallest events. The flare centroid position are found at the peak time and as a function of energy (3-6, 6-12, 12-25 keV). Flares are found to occur only in active regions, not in the "quiet" Sun. Flare heights are found using two independent methods including that of Matsushita (1992). The distribution of flares at the limb are fitted with a Monte Carlo simulations and the flare height deduced. We find that the 6-12 keV flare heights are consistent with a flare height of ~3 arcseconds above the photosphere with small separation between the thermal and nonthermal sources. The Matsushita method confirm these values.

The equations of motion for the rotor are derived using an integral Newtonian method, which ..... (modulus weighted centroid) is on the x axis, at a distance xC aft of the ...... coning degree of freedom., while S,C and S,S are the tip-path-plane tilt ...... the pitch horn and pitch link are given by the angles KPH + 0 75 and APL.

We present a new three-dimensional hybrid level set (LS) and volume of fluid (VOF) method for free surface flow simulations on tetrahedral grids. At each time step, we evolve both the level set function and the volume fraction. The level set function is evolved by solving the level set advection equation using a second-order characteristic based finite volume method. The volume fraction advection is performed using a bounded compressive normalized variable diagram (NVD) based scheme. The interface is reconstructed based on both the level set and the volume fraction information. The novelty of the method lies in that we use an analytic method for finding the intercepts on tetrahedral grids, which makes interface reconstruction efficient and conserves volume of fluid exactly. Furthermore, the advection of volume fraction makes use of the NVD concept and switches between different high resolution differencing schemes to yield a bounded scalar field, and to preserve both smoothness and sharp definition of the interface. The method is coupled to a well validated finite volume based Navier-Stokes incompressible flow solver. The code validation shows that our method can be employed to resolve complex interface changes efficiently and accurately. In addition, the centroid and intercept data available as a by-product of the proposed interface reconstruction scheme can be used directly in near-interface sub-grid models in large eddy simulation.

(Modified) The scaling of velocity fluctuation, dv, as a function of spatial scale L in molecular clouds can be measured from size-linewidth relations, principal component analysis, or line centroid variation. Differing values of the power law index of the scaling relation dv = L^(g3D) in 3D are given by these different methods: the first two give g3D=0.5, while line centroid analysis gives g3D=0. This discrepancy has previously not been fully appreciated, as the variation of projected velocity line centroid fluctuations (dv_{lc} = L^(g2D)) is indeed described, in 2D, by g2D=0.5. However, if projection smoothing is accounted for, this implies that g3D=0. We suggest that a resolution of this discrepancy can be achieved by accounting for the effect of density inhomogeneity on the observed g2D obtained from velocity line centroid analysis. Numerical simulations of compressible turbulence are used to show that the effect of density inhomogeneity statistically reverses the effect of projection smoothing in the cas...

NEAT is an astrometric mission proposed to ESA with the objectives of detecting Earth-like exoplanets in the habitable zone of nearby solar-type stars. In NEAT, one fundamental aspect is the capability to measure stellar centroids at the precision of 5 {\\times} 10-6 pixel. Current state-of-the-art methods for centroid estimation have reached a precision of about 4 {\\times} 10-5 pixel at Nyquist sampling. Simulations showed that a precision of 2 {\\mu}-pixels can be reached, if intra and inter pixel quantum efficiency variations are calibrated and corrected for by a metrology system. The European part of the NEAT consortium is designing and building a testbed in vacuum in order to achieve 5 {\\times} 10-6 pixel precision for the centroid estimation. The goal is to provide a proof of concept for the precision requirement of the NEAT spacecraft. In this paper we give the basic relations and trade-offs that come into play for the design of a centroid testbed and its metrology system. We detail the different conditi...

This paper proposes a method for recognizing hand-shapes by using multi-viewpoint image sets. The recognition of a hand-shape is a difficult problem, as appearance of the hand changes largely depending on viewpoint, illumination conditions and individual characteristics. To overcome this problem, we apply the Kernel Orthogonal Mutual Subspace Method (KOMSM) to shift-invariance features obtained from multi-viewpoint images of a hand. When applying KOMSM to hand recognition with a lot of learning images from each class, it is necessary to consider how to run the KOMSM with heavy computational cost due to the kernel trick technique. We propose a new method that can drastically reduce the computational cost of KOMSM by adopting centroids and the number of images belonging to the centroids, which are obtained by using k-means clustering. The validity of the proposed method is demonstrated through evaluation experiments using multi-viewpoint image sets of 30 classes of hand-shapes.   

Lignin concentrations from wood pulp samples are measured by applying an excitation light at a selected wavelength to the samples in order to cause the lignin to emit fluorescence. A spectral distribution of the fluorescence emission is then determined. The lignin concentration is then calculated based on the spectral distribution signal. The spectral distribution is quantified by either a wavelength centroid method or a band ratio method.

Electromagnetic (EM) tracking has been recognized as a valuable tool for locating the interventional devices in procedures such as lung and liver biopsy or ablation. The advantage of this technology is its real-time connection to the 3D volumetric roadmap, i.e. CT, of a patient's anatomy while the intervention is performed. EM-based guidance requires tracking of the tip of the interventional device, transforming the location of the device onto pre-operative CT images, and superimposing the device in the 3D images to assist physicians to complete the procedure more effectively. A key requirement of this data integration is to find automatically the mapping between EM and CT coordinate systems. Thus, skin fiducial sensors are attached to patients before acquiring the pre-operative CTs. Then, those sensors can be recognized in both CT and EM coordinate systems and used calculate the transformation matrix. In this paper, to enable the EM-based navigation workflow and reduce procedural preparation time, an automatic fiducial detection method is proposed to obtain the centroids of the sensors from the pre-operative CT. The approach has been applied to 13 rabbit datasets derived from an animal study and eight human images from an observation study. The numerical results show that it is a reliable and efficient method for use in EM-guided application.

In the conventional centroid position estimation method, the effective field of view (FOV) of a scintillation bar-detector cannot be extended beyond the centers of the two outside PMTs. To extend the FOV, the authors have implemented statistical position estimation on a bar-detector with blackened end surfaces. Maximum Likelihood (ML) and Minimum Square Error (MSE) position estimation look up tables (LUTs) were calculated from experimentally measured histogram data. Both statistical estimators provide a 14 cm FOV on a 16 cm bar, with 4 to 6 mm FWHM within the FOV. In contrast, the centroid method provides a 10cm FOV on a conventional bar detector. In order to reduce the size of LUTs and memory requirements, they have demonstrated the feasibility of using local, 2-D LUTs for position estimation. Using statistical position estimation methods and scatter-free sources they were able to extend the FOV beyond the conventional limit to utilize 90% of the bar-detector area.

BACKGROUND: Femoroacetabular impingement (FAI) can lead to labral injury, osseous changes, and even osteoarthritis. The literature contains inconsistent definitions of the alpha angle and other nonthree-dimensional (3-D) radiographic measures. We present a novel approach to quantifying cam lesions in 3-D terms. Our method also can be used to develop a classification system that describes the exact location and size of cam lesions. QUESTIONS/HYPOTHESES: We asked whether automated quantification of CAM lesions based on CT data is a reasonable way to detect CAM lesions and whether they may be classified based on location. METHOD OF STUDY: We developed a method to quantify femoral head cam lesions using 3-D modeling of CT scans. By segmenting raw DICOM data, we can determine the distance from the cam lesion's surface points to the centroid of the femoral head to quantify the mean bump height, volume, and location. The resulting 3-D femoral and acetabular models will be analyzed with custom software. We then will quantify the cam lesion with 3-D parameters using a modified zoning method. The mean bump height, volume, and location on the clock face, and relative zoning will be calculated. Zonal differences will be statistically analyzed. To assess the ability of this method to predict arthroscopic findings, we will obtain preoperative CT scans for 25 patients who undergo hip arthroscopy for FAI. We will compare measurements with the method with our measurements from arthroscopy. The clinical implications of our method's measurements then will be reviewed and refined for future prospective studies. SIGNIFICANCE: We present a novel approach that can quantify a cam lesion's location and size. This method will be used to provide guidelines for the exact amount of bony resection needed from a specific location of the proximal femur. There is also potential to develop software for ease of use so this method can be more widely applied. PMID:23129477

A novel method of using hard X-rays as a diagnostic for chromospheric density and magnetic structures is developed to infer sub-arcsecond vertical variation of magnetic flux tube size and neutral gas density.Using Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) X-ray data and the newly developed X-ray visibilities forward fitting technique we find the FWHM and centroid positions of hard X-ray sources with sub-arcsecond resolution ($\\sim 0.2"$) for a solar limb flare. We show that the height variations of the chromospheric density and the magnetic flux densities can be found with unprecedented vertical resolution of $\\sim$ 150 km by mapping 18-250 keV X-ray emission of energetic electrons propagating in the loop at chromospheric heights of 400-1500 km. Our observations suggest that the density of the neutral gas is in good agreement with hydrostatic models with a scale height of around $140\\pm 30$ km. FWHM sizes of the X-ray sources decrease with energy suggesting the expansion (fanning out) of m...

The joint hypocentral determination method is used to relocate deep seismicity reported in the International Seismological Center catalog for earthquakes deeper than 400 km in the Honshu, Bonin, Mariannas, Java, Banda, and South America subduction zones. Each deep seismic zone is found to display planar features of seismicity parallel to the Harvard centroid-moment tensor nodal planes, which are identified as planes of shear failure. The sense of displacement on these planes is one of resistance to deeper penetration.

This paper investigates the problem of designing a codebook with non-uniform power allocation for multimode precoded MIMO schemes(e.g., spatial multiplexing and STBC) with limited feedback in fading channels. The generalized Lloyd algorithm is employed for the design, and two methods with different complexities are addressed for the computation of the centroid which is formulated as an optimization problem. Numerical results show that the proposed design outperforms comparable algorithms which equally allocate the total transmit power to each data stream.   

Purpose To determine the position of rectus muscle pulleys in Japanese eyes and to evaluate the effect of oblique muscle surgery on rectus muscle pulleys. Methods Quasi-coronal plane MRI was used to determine area centroids of the 4 rectus muscles. The area centroids of the rectus muscles were transformed to 2-dimensional coordinates to represent pulley positions. The effects of oblique muscle surgery on the rectus muscle pulley positions in the coronal plane were evaluated in 10 subjects with cyclovertical strabismus and, as a control, pulley locations in 7 normal Japanese subjects were calculated. Results The mean positions of the rectus muscle pulleys in the coronal plane did not significantly differ from previous reports on normal populations, including Caucasians. There were significa...

Abstract Despite the general increase in digital techniques for dental morphometric analyses, only a few methods are available to study worn teeth. Moreover, permanent dentitions are studied much more frequently than deciduous teeth. In this study, we address both issues by providing a taxonomic classification of Neanderthal and modern human (MH) lower second deciduous molars (dm2s) through the analysis of crown and cervical outlines. Crown and cervical outlines were obtained from a three-dimensional (3D) digital sample of uniformly oriented dm2s. Both outlines were centered on the centroid of their area and represented by 16 pseudolandmarks obtained by equiangularly spaced radial vectors out of the centroid. We removed size information from the oriented and centered outlines with a unifor...

Purpose: To evaluate the use of megavoltage cone-beam computed tomography (MV CBCT) to measure interfractional variation in lung tumor position. Methods and Materials: Eight non-small-cell lung cancer patients participated in the study, 4 with respiratory gating and 4 without. All patients underwent MV CBCT scanning at weekly intervals. Contoured planning CT and MV CBCT images were spatially registered based on vertebral anatomy, and displacements of the tumor centroid determined. Setup error was assessed by comparing weekly portal orthogonal radiographs with digitally reconstructed radiographs generated from planning CT images. Hypothesis testing was performed to test the statistical significance of the volume difference, centroid displacement, and setup uncertainty. Results: The vertebral bodies and soft tissue portions of tumor within lung were visible on the MV CBCT scans. Statistically significant systematic volume decrease over the course of treatment was observed for 1 patient. The average centroid displacement between simulation CT and MV CBCT scans were 2.5 mm, -2.0 mm, and -1.5 mm with standard deviations of 2.7 mm, 2.7 mm, and 2.6 mm in the right-left, anterior-posterior and superior-inferior directions. The mean setup errors were smaller than the centroid shifts, while the standard deviations were comparable. In most cases, the gross tumor volume (GTV) defined on the MV CBCT was located on average at least 5 mm inside a 10 mm expansion of the GTV defined on the planning CT scan. Conclusions: The MV CBCT technique can be used to image lung tumors and may prove valuable for image-guided radiotherapy. Our conclusions must be verified in view of the small patient number.

Purpose: To characterize the interfractional variability in lung tumor volume, position, and tumor boundaries.Methods: Cone-beam computed tomography (CBCT) scans were acquired weekly during the course of treatment for 34 lung cancer patients (1-20 scans) with large tumors. Spatial registration based on bones was performed between contoured planning CT and CBCT. Gross tumor volume (GTV) on each CBCT was then contoured. Tumor volume, centroid, and boundaries variability were quantified. A commercial deformable registration software was tested and results were compared to manual contours.Results: Mean volume reduction was 41 ± 32% (p < 0.001) after an average time of 51 days. Tumor centroid drifts were 0.03, 0.14, and -0.13 cm in right-left (RL), anterior-posterior (AP), and superior-inferior (SI) directions with standard deviations of 0.55, 0.50, and 0.51 cm. GTV boundaries displacements were -0.27, -0.14, and -0.16 cm with standard deviations of 0.64, 0.57, and 0.59 cm in RL, AP, and SI directions. Relative error between deformed and manual contours with the commercial deformable registration software rose up exponentially with the GTV decrease.Conclusions: GTV size changes for large lung tumors are similar to those for standard tumors. Magnitude absolute values of displacement vector for centroid and boundaries shifts show that there is not a preferred direction for the drifts but shrinkage. PMID:23127097

Anisotropic triangle meshes are used for efficient approximation of surfaces and flow data in finite element analysis, and in these applications it is desirable to have as few obtuse triangles as possible to reduce the discretization error. We present a variational approach to suppressing obtuse triangles in anisotropic meshes. Specifically, we introduce a hexagonal Minkowski metric, which is sensitive to triangle orientation, to give a new formulation of the centroidal Voronoi tessellation (CVT) method. Furthermore, we prove several relevant properties of the CVT method with the newly introduced metric. Experiments show that our algorithm produces anisotropic meshes with much fewer obtuse triangles than using existing methods while maintaining mesh anisotropy.

Node generation plays an important role in meshless methods for seepage analysis with a free surface. A probabilistic algorithm based on a combination of simulated annealing and the generalized probabilistic Lloyd's method, which is related to centroidal Voronoi tessellations (CVTs), is used in seepage analyses with the element-free Galerkin method (EFG). The applications in this paper involve analyzing steady seepage in a rectangular dam, a dam with an inclined slope surface, and a dam with a horizontal drain. The results show that the algorithm can easily fit and update the changeable free surface, and obtains higher-quality node sets, particularly when simulating physical domains with complex geometrical boundaries.

This paper analyses the occipital remains recovered from the El Sidrón (Asturias, Spain) Neandertal site between the years of 2000-2008. The sample is represented by three specimens, SD-1219, SD-1149, and SD-370a. Descriptive morphology, linear measurements, 3D geometric morphometrics, and virtual anthropological methods were employed to address the morphological, morphometric, and phylogenetic affinities of these fossils. The fossils display Neandertal autapomorphies (e.g., bilaterally protruding transverse occipital torus, suprainiac fossa). SD-1219 also preserves a strongly projecting juxtamastoid eminence and shows occipital bunning. In linear distances, the El Sidrón occipitals are similar to each other and close to the Neandertal mean. The centroid size of SD-1219 is slightly larger than the Neandertal average. All of the evidence taken together points to the hypothesis that SD-1219 belongs to a smaller Neandertal male. Linear measurements and the vault thickness of SD-1149 also suggest a robust male individual. The gracility of SD-370a points towards an immature individual. Virtual anthropological methods were used to reconstruct a 3D model of the SD-1219 occipital for geometric morphometrics, which reveals that SD-1219 shows relatively broad and low occipital plane proportions. Within the European Pleistocene lineage sample, this fossil falls geometrically closer to primitive rather than to derived morphologies because of its increased width, and a lower, anterior position of inion relative to the biasterionic axis. These results may imply that cranial sphericity could be an important feature of intraspecific Neandertal variability. Our findings open the way for further studies of intraspecific variation in Neandertal populations, in which the El Sidrón sample may play a significant role. PMID:19836056

A simple method for the rapid identification of inorganic salts used as raw materials during food production has been established using energy dispersive X-ray fluorescence (EDXRF). Intensities of Na, Mg, P, S, Cl, K, Ca, Mn, Fe, Cu, Zn K? peaks have been measured. The treatment and comparison of the respective intensities allowed a rapid identification of inorganic salts. Two different methods of data treatment have been tested: K nearest neighbours (KNN) and centroids. Using cross validation on a database containing 140 samples representing 31 classes, a total of 98% of samples were well identified.   

We mainly employ centroid-moment tensor solutions (CMTs) for the March 11, 2011 Tohoku Earthquake and its aftershocks reported by Harvard University in studying deformation and stress state around Japan Sea area. After confirming the validity of CMTs by P-wave first motion polarity data from IRIS, we do cluster analysis and find that the solutions can be divided into three groups. The first group events are the kind of the main shock which is a low-angle thrust event, mainly occurred on the interface between the Pacific Plate and the North American Plate. The second group events are normal-fault earthquakes with principal extensional directions roughly pointing East-West direction. Most of these earthquakes located in the forearc uplift region of the Pacific plate. Some others occurred in the forearc accretionary wedge. The third group events are also normal-fault earthquakes though their principal extensional directions are roughly along the direction of the trench. These events located to the west of the Japan trench. We employ finite element method to simulate the stress state and deformation revealed by the focal mechanism solutions as well as GPS observations. Results show that the March 11, 2011 Tohoku Earthquake and some of its aftershocks released much of the East-West directional compressional stress accumulated in hundreds of years and resulted in at least a temporary East-West tensile state in the Japan Sea region which extends to China mainland. The normal-fault aftershocks located to the west of the Japan trench with East-West principal extensional direction were produced by this stress condition, while the existence of the normal-fault aftershocks with North-South principal extensional direction expressed the values of the tension along North-South direction and along East-West direction are roughly equal.

The spectral centroid of a signal is the curve whose value at any given time is the centroid of the corresponding constant-time cross section of the signal???s spectrogram. A spectral centroid provides a noise-robust estimate of how the dominant frequency of a signal changes over time. As such, spectral centroids are an increasingly popular tool in several signal processing applications, such as speech processing. We provide a new, fast and accurate algorithm for the real-time computation of the spectral centroid of a discrete-time signal. In particular, by exploiting discrete Fourier transforms, we show how one can compute the spectral centroid of a signal without ever needing to explicitly compute the signal???s spectrogram. We then apply spectral centroids to an emerging biometrics prob...

Mormon prophet Joseph Smith (1805–44) claimed that more than two-dozen ancient individuals (Nephi, Mormon, Alma, etc.) living from around 2200 BC to 421 AD authored the Book of Mormon (1830), and that he translated their inscriptions into English. Later researchers who analyzed selections from the Book of Mormon concluded that differences between selections supported Smith's claim of multiple authorship and ancient origins. We offer a new approach that employs two classification techniques: ‘delta’ commonly used to determine probable authorship and ‘nearest shrunken centroid’ (NSC), a more generally applicable classifier. We use both methods to determine, on a chapter-by-chapter basis, the probability that each of seven potential authors wrot...

Environmental pollution is a worldwide problem, and metals are the largest group of contaminants in soil. Microarray toxicogenomic studies with ecologically relevant organisms, such as springtails, supplement traditional ecotoxicological research but are presently rather descriptive. Classifier analysis, a more analytical application of the microarray technique, is able to predict biological classes of unknown samples. We used the uncorrelated shrunken centroid method to classify gene expression profiles of the springtail Folsomia candida exposed to soil spiked with six different metals (barium, cadmium, cobalt, chromium, lead, and zinc). We identified a gene set (classifier) of 188 genes that can discriminate between six different metals present in soil, which allowed us to predict the co...

In this manuscript we present an automated algorithm for the alignment of thoracic scans using descriptors of bone structures. Bone structures were utilized because they are expected to be less susceptible to sources of errors such as patient positioning and breath hold. The algorithm employed the positioning of ribs relative to the spinal cord along with a description of the scapula. The spinal cord centroid was detected by extracting local maxima of the distance transform followed by point tracing along consecutive slices. Ribs were segmented using adaptive thresholding followed by the watershed algorithm to detach ribs from the vertebra, and by imposing requirements of rib proximity to the lung border. The angles formed between the spinal cord centroid and segmented rib centroids were used to describe rib positioning. Additionally, the length of the scapula was extracted in each slice. A cost function incorporating the difference of features from rib positioning and scapula length between two slices was derived and used to match slices. The method was evaluated on a set of 12 pairs of full and partial CT scans acquired on the same day. Evaluation was based on whether the slices showing a nodule at its maximum diameter in each scan were matched. Full-to-partial and partial-to-full alignment were performed. Results showed that the proposed metric matched nodule slices within an average distance of 1.08 and 1.17 slices from the target for full-to-partial and partial-to-full alignment respectively. These preliminary results are encouraging for using this method as a first step in an overall process of temporally analyzing CT lung nodules.

We model the motility of Dictyostelium cells in a systematic data-driven manner. We deduce a minimal dynamical model that reproduces the statistical features of experimental trajectories. These are trajectories of the centroid of the cell perimeter, which is more sensitive to pseudopod activity than the usual tracking by centroid or nucleus. Our data account for cell individuality and dictate a model that extends the cell-type specific models recently derived for mammalian cells. Two generalized Langevin equations model stochastic periodic pseudopod motion parallel and orthogonal to the amoeba's direction of motion. This motion propels the amoeba with a random periodic left–right waddle in a direction that has a long persistence time. The model fully accounts for the statistics of the experimental trajectories, including velocity power spectra and auto-correlations, non-Gaussian velocity distributions, and multiplicative noise. Thus, we find neither need nor place in our data for an interpretation in terms ofanomalous diffusion. The model faithfully captures cell individuality as different parameter values in the model, and serves as a basis for integrating the local mechanics of cell motion with our observed long-term behavior.

We study the nuclear isoscalar monopole and dipole compression modes in nuclei within the fluid dynamic approach (FDA) with and without the effect of relaxation. For a wide region of the medium and heavy nuclei, the FDA predicts that the isoscalar giant monopole resonance (ISGMR) and the isoscalar giant dipole resonance (ISGDR) exhaust about 90% of the corresponding model-independent sum rules. In the case of neglecting the effect of relaxation, the FDA, when adjusted to reproduce the centroid energy E0 of the ISGMR, results with centroid energy E1 of the ISGDR which is in agreement with the predictions of the self-consistent Hartree-Fock random-phase approximation calculations and the scaling model but significantly larger than the experimental value. We also show that the FDA leads to the correct hydrodynamic limit for the ratio (E1/E0){sub FDA}. We find that the ratio (E1/E0){sub FDA} depends on the relaxation time and approaches the preliminary experimental value (E1/E0){sub exp}=1.5{+-}0.1 in a short relaxation time limit. (c) 2000 The American Physical Society.

Characterization and modeling of subsurface flow and transport properties is critical for modeling, performance prediction and design of a number of important environmental and energy applications, including groundwater flow and contaminant transport, energy recovery from geothermal and hydrocarbon reservoirs, and geologic storage of CO2. Inverse modeling is typically applied to infer hydraulic rock properties from available static and dynamic measurements. Data sparsity and nonlinearity with respect to model parameters often result in significant uncertainty and solution non-uniqueness in solving the resulting inverse problems. Stochastic methods have become increasingly popular for dealing with inverse modeling solution non-uniqueness and uncertainty quantification. In particular, the ensemble Kalman filter (EnKF) has been widely applied for stochastic characterization of aquifer hydraulic properties from dynamic field measurements. For practical applications, where large-scale models are used, the computational cost of the forward simulation severely constrains the number of model realizations that can be included in ensemble predictions. Consequently, the statistics computed from a limited-size ensemble becomes spurious, making the resulting EnKF model updates unreliable. Localization and local analysis methods have been introduced to mitigate the effect of spurious correlations by reducing or removing the unphysical numerical correlations between model parameters (and/or states) and observations at distant locations. While these methods have proven useful, they require prior tuning of localization parameters and do not address the impact of small ensemble size approximation on the existing physical correlations between parameters and close-by observations. An alternative approach to localization is to approximate the correct statistics from computationally efficient surrogate models. Here, we present an efficient streamline-based pseudo forecast method for approximation of the first and second order statistics needed for EnKF-based model calibration. We accomplish this by first performing fast streamline simulation for a large ensemble of models and cluster them into a small number of groups based on their flow responses. We then perform full simulations with the representative models in each cluster (cluster centroids) and use them to find correlations between the forecasts obtained from streamline and full simulation. These correlations are then used to adjust streamline-based forecasts for all realizations, which are in turn used to compute the second order sample statistics needed for the EnKF updates. We examine the performance of the proposed approach using several three dimensional three-phase subsurface flow models and compare the results with those obtained from the full simulation. We demonstrate the effectiveness and practicality of the proposed method for large-scale model calibration with EnKF.

Digital particle image velocimetry and fluorescent dye visualization are used to characterize the performance of fish-like swimming robots. During nominal swimming, these robots produce a ‘V’-shaped double wake, with two reverse-Kármán streets in the far wake. The Reynolds number based on swimming speed and body length is approximately 7500, and the Strouhal number based on flapping frequency, flapping amplitude, and swimming speed is 0.86. It is found that swimming speed scales with the strength and geometry of a composite wake, which is constructed by freezing each vortex at the location of its centroid at the time of shedding. Specifically, we find that swimming speed scales linearly with vortex circulation. Also, swimming speed scales linearly with flapping frequency and the width of the composite wake. The thrust produced by the swimming robot is estimated using a simple vortex dynamics model, and we find satisfactory agreement between this estimate and measurements made during static load tests.

Displacement time-series recorded by Global Positioning System (GPS) receivers are a new type of near-field waveform observation of the seismic source. We have developed an inversion method which enables the recovery of an earthquake's mechanism and centroid coordinates from such data. Our approach is identical to that of the 'classical' Centroid-Moment Tensor (CMT) algorithm, except that we forward model the seismic wavefield using a method that is amenable to the efficient computation of synthetic GPS seismograms and their partial derivatives. We demonstrate the validity of our approach by calculating CMT solutions using 1 Hz GPS data for two recent earthquakes in Japan. These results are in good agreement with independently determined source models of these events. With wider availability of data, we envisage the CMT algorithm providing a tool for the systematic inversion of GPS waveforms, as is already the case for teleseismic data. Furthermore, this general inversion method could equally be applied to other near-field earthquake observations such as those made using accelerometers.

We have constructed a photoelectron imaging spectrometer with super-resolution image processing and have applied it to the photoionization of nitric oxide and benzene in molecular beams. A field programmable gate array is employed for real-time subpixel centroiding calculations on hardware, providing 64 megapixel resolution (8192 × 8192 pixels). We examined eight different centroiding algorithms based on the center-of-gravity (COG) and Gaussian fitting (Gauss) methods and have found that the two-dimensional COG (2D-COG) and weighted mean of Gaussian center (w-Gauss) methods have the best performance. The excellent performance of the instrument is demonstrated by visualizing a 25 ?m diameter pore structure of an MCP, indicating a spatial resolution of 0.03%. The photoelectron image in one-color (1 + 1) resonance-enhanced multiphoton ionization of nitric oxide using a nanosecond laser provided a photoelectron kinetic energy resolution of 0.2%. This resolution is currently restricted by charged-particle optics. The photoelectron energy and angular distributions in the one-color (1 + 1) resonance-enhanced multiphoton ionization of benzene via 61 and 6111 vibronic levels in the S1 state are also presented. The results demonstrate that photoelectron angular anisotropy varies with the photoelectron kinetic energy and the vibronic state of the cation.

Rainfall is regarded as the most important input for the hydrology and nonpoint source (H/NPS) models and uncertainty related to rainfall is generally recognized as a major challenge in watershed modeling. In this paper, we focus on the impact of spatial rainfall variability on H/NPS modeling of a large watershed. The uncertainty introduced by spatial rainfall variability was determined using a number of commonly-used interpolation methods: (1) the Centroid method; (2) the Thiessen Polygon method; (3) the Inverse Distance Weighted (IDW) method; (4) the Dis-Kriging method; and (5) the Co-Kriging method. The Soil and Water Assessment tool (SWAT) was used to quantify the effect of rainfall spatial variability on watershed H/NPS modeling of the Daning watershed in China. Results indicated that...

A recently developed Centroidal Voronoi Tessellation (CVT) unstructured sampling method is investigated here to assess its suitability for use in statistical sampling and function integration. CVT efficiently generates a highly uniform distribution of sample points over arbitrarily shaped M-Dimensional parameter spaces. It has recently been shown on several 2-D test problems to provide superior point distributions for generating locally conforming response surfaces. In this paper, its performance as a statistical sampling and function integration method is compared to that of Latin-Hypercube Sampling (LHS) and Simple Random Sampling (SRS) Monte Carlo methods, and Halton and Hammersley quasi-Monte-Carlo sequence methods. Specifically, sampling efficiencies are compared for function integration and for resolving various statistics of response in a 2-D test problem. It is found that on balance CVT performs best of all these sampling methods on our test problems.

An Interactive Cluster Analysis Procedure (ICAP) was developed to derive classifier training statistics from remotely sensed data. The algorithm interfaces the rapid numerical processing capacity of a computer with the human ability to integrate qualitative information. Control of the clustering process alternates between the algorithm, which creates new centroids and forms clusters and the analyst, who evaluate and elect to modify the cluster structure. Clusters can be deleted or lumped pairwise, or new centroids can be added. A summary of the cluster statistics can be requested to facilitate cluster manipulation. The ICAP was implemented in APL (A Programming Language), an interactive computer language. The flexibility of the algorithm was evaluated using data from different LANDSAT scenes to simulate two situations: one in which the analyst is assumed to have no prior knowledge about the data and wishes to have the clusters formed more or less automatically; and the other in which the analyst is assumed to have some knowledge about the data structure and wishes to use that information to closely supervise the clustering process. For comparison, an existing clustering method was also applied to the two data sets.

The 3-D luminosity distribution at the IP of the SLAC B-Factory is monitored using e{sup +}e{sup -} {yields} e{sup +}e{sup -}, {mu}{sup +}{mu}{sup -} events reconstructed online in the BABAR detector. The transverse centroid and spatial orientation of the luminosity ellipsoid reliably monitor IP orbit drifts. The longitudinal centroid is sensitive to small variations in the average relative RF phase of the beams and provides a detailed measurement of the phase transient along the bunch train. The longitudinal luminosity distribution depends on the e{sup +,-} overlap bunch length and the vertical IP {beta}-functions. Relative variations in horizontal luminous size are detectable at the micron level. In addition to continuous on-line monitoring of all the parameters above, we performed detailed studies of their variation along the bunch train to investigate a temporary luminosity degradation. We also compare {beta}*{sub y} measurements, collected over a year of high-luminosity operation, with HER and LER lattice functions measured by resonant transverse excitation. Our bunch-length measurements are consistent with those obtained by other methods and provide direct evidence for bunch-length modulation.

A new detector module has been developed for a prototype system, McSPECT 2, which is being constructed for high-resolution clinical brain imaging. The detector module is the building block of the cylindrical detector system of the McSPECT 2. Each detector module contains 5 NaI(Tl) bars and is backed by a glass window in an aluminum housing. Each detector module is associated with 6 PMTs to form a functional unit for position estimation. Bench-top tests performed on a sample unit demonstrated an average of 10.5% local energy resolution (ER) at 140 keV. Centroid calculations were applied in both orthogonal directions of the module for position estimation. In the longitudinal direction, a two-step centroid method yields a 13 cm UFOV (useful field-of-view) along the bar and an 11 cm CFOV (center FOV), with intrinsic spatial resolution of < 5.5 and 3.8 [+-] 0.3 mm FWHM, respectively. In the transverse direction, the task of identifying the bar detector involved in an event is simplified, with an accuracy better than 99% when photons are incident normally.

A two-dimensional finite element method for an incompressible two-fluid model is developed in order to enhance the applicability of the two-fluid model to the analyses in arbitrarily shaped channels. The solution algorithm is based on the SMAC method for incompressible single-phase flows. Quadrilateral element with four nodes is employed. The velocities and volumetric fractions of both phases are defined on the nodes. The pressure is defined at a centroid of each element and assumed to be constant within the element. The Galerkin method is applied to the finite element formulations. Air-water two-phase flow around a circular cylinder is analyzed by the finite element method. The calculated distributions of the volumetric fraction of the gas-phase show good agreement with measurements. (author).

This paper considers selection of urban freeway ramps and routes based on user equilibrium in a single nucleus city of dispersive and continuous structure, and attempts an estimation of the ramp catchment area. The proposed method is a simultaneous estimation model that explains from trips taking place continuously in an urban area to distributed traffic amount in one model. The model features that it considers traffic congestions and demand variation and that the user equilibrium condition is satisfied by the ramp catchment area and utilized traffic amount, and determined endogenously by the model. This method expresses the freeways in the ordinarynetworks, as well as uses a continuum expression on surface roads that are distributed densely. Such a continuum expression method hypothesizes that an urban area has a continuous trip generation density, and differs from the conventional analytical methods, which divide the object area into zones, and hypothesize centroids with each zone as the center. 15 refs., 8 figs., 3 tabs.

We have developed a technique for automatically identifying the script used to generate a document that is stored electronically in bit image form. Our approach differs from previous work in that the distinctions among scripts are discovered by an automatic learning procedure, without any handson analysis. We first develop a set of representative symbols (templates) for each script in our database (Cyrillic, Roman, etc.). We do this by identifying all textual symbols in a set of training documents, scaling each symbol to a fixed size, clustering similar symbols, pruning minor clusters, and finding each cluster`s centroid. To identify a new document`s script, we identify and scale a subset of symbols from the document and compare them to the templates for each script. We choose the script whose templates provide the best match. Our current system distinguishes among the Armenian, Burmese, Chinese, Cyrillic, Ethiopic, Greek, Hebrew, Japanese, Korean, Roman, and Thai scripts with over 90% accuracy.

In this paper, the uncertainties of gamma-ray small peak analysis have been examined. As the intensity of a gamma-ray peak approaches its detection decision limit, derived parameters such as centroid channel energy, peak area, peak area uncertainty, baseline determination, and peak significance are statistically sensitive. The intercomparison exercise organized by the CTBTO provided an excellent opportunity for this to be studied. Near background levels, the false-positive and false-negative peak identification frequencies in artificial test spectra have been compared to statistically predictable limiting values. In addition, naturally occurring radon progeny were used to compare observed variance against nominal uncertainties. The results infer that the applied fit algorithms do not always represent the best estimator. Understanding the statistically predicted peak-finding limit is important for data evaluation and analysis assessment. Furthermore, these results are useful to optimize analytical procedures to achieve the best results. PMID:18515125

Summary Here, we present the results of a genetic analysis of 463 Pottoka ponies corresponding to four generations, using 17 microsatellite markers. Ten years after the beginning of the Pottoka conservation programme, the values for the genetic diversity of the breed are still high and stable, indicating the success of the programme. We found null alleles in Pottoka for the ASB23, HMS3 and HTG10 microsatellites. Together with information obtained from other pony breeds from the Iberian Peninsula, this finding indicates that these microsatellites should not be used for phylogenetic analyses or parentage tests, at least for these breeds. The high heterozygosity exhibited by this breed in comparison to other ponies, together with its genetic proximity to the centroid of the allele frequencies...

We establish a general propagation model to describe the spin Hall effect of light beam in left-handed materials (LHMs). A spin-dependent shift of the beam centroid perpendicular to the refractive index gradient for the light beam through an air-LHM interface is demonstrated. For a certain circularly polarized component, whether the transverse shift is positive or negative depends on the magnitude of the refractive index gradient. Very surprisingly, the spin Hall effect in the LHM is unreversed, although the sign of refractive index gradient is reversed. The physics underlying this counterintuitive effect is that the spin angular momentum of photons is unreversed. Further, we reveal that the angular shift in the LHM is reversed due to the negative diffraction. These findings provide alternative evidence for that the linear momentum of photons is reversed, while the spin angular momentum is unreversed in the LHM.

A multiwire proportional chamber system has been built as an area detector for use in X-ray crystallography with Cu K/sub alpha / radiation (1.54AA). The chamber, constructed by Charpak and collaborators at CERN, consists of a 10cm thick spherical interaction region with a radial electric field, a transition from spherical to plane geometry and a 50cm*50cm multiwire proportional chamber and subtends a 90 degrees opening angle. Two dimensional position information is obtained from orthogonal cathode planes using a high speed analog centroid finding technique. Data on spatial and energy resolution as a function of angle and depth of interaction in the spherical drift region using a collimated, pulsed, X-ray source are presented. Ionization loss as a function of drift distance and field and loss due to field shaping grids has also been measured. (6 refs).

In this paper, we describe an automated integration-free path-integral (AIF-PI) method, based on Kleinert's variational perturbation (KP) theory, to treat internuclear quantum-statistical effects in molecular systems. We have developed an analytical method to obtain the centroid potential as a function of the variational parameter in the KP theory, which avoids numerical difficulties in path-integral Monte Carlo or molecular dynamics simulations, especially at the limit of zero-temperature. Consequently, the variational calculations using the KP theory can be efficiently carried out beyond the first order, i.e., the Giachetti-Tognetti-Feynman-Kleinert variational approach, for realistic chemical applications. By making use of the approximation of independent instantaneous normal modes (INM), the AIF-PI method can readily be applied to many-body systems. Previously, we have shown that in the INM approximation, the AIF-PI method is accurate for computing the quantum partition function of a water molecule (3 degrees of freedom) and the quantum correction factor for the collinear H(3) reaction rate (2 degrees of freedom). In this work, the accuracy and properties of the KP theory are further investigated by using the first three order perturbations on an asymmetric double-well potential, the bond vibrations of H(2), HF, and HCl represented by the Morse potential, and a proton-transfer barrier modeled by the Eckart potential. The zero-point energy, quantum partition function, and tunneling factor for these systems have been determined and are found to be in excellent agreement with the exact quantum results. Using our new analytical results at the zero-temperature limit, we show that the minimum value of the computed centroid potential in the KP theory is in excellent agreement with the ground state energy (zero-point energy) and the position of the centroid potential minimum is the expectation value of particle position in wave mechanics. The fast convergent property of the KP theory is further examined in comparison with results from the traditional Rayleigh-Ritz variational approach and Rayleigh-Schrödinger perturbation theory in wave mechanics. The present method can be used for thermodynamic and quantum dynamic calculations, including to systematically determine the exact value of zero-point energy and to study kinetic isotope effects for chemical reactions in solution and in enzymes. PMID:19749977

A new stable unstructured finite volume method is presented for parallel large-scale simulation of viscoelastic fluid flows. The numerical method is based on the side-centered finite volume method where the velocity vector components are defined at the mid-point of each cell face, while the pressure term and the extra stress tensor are defined at element centroids. The present arrangement of the primitive variables leads to a stable numerical scheme and it does not require any ad-hoc modifications in order to enhance the pressure-velocity-stress coupling. The log-conformation representation proposed in [R. Fattal, R. Kupferman, Constitutive laws for the matrix-logarithm of the conformation tensor, J. Non-Newtonian Fluid Mech. 123 (2004) 281-285] has been implemented in order improve the li...

This paper presents the evaluation of the effect of the method of ECG signal encoding, based on nonlinear characteristics such as information entropy and Lempel-Ziv complexity, on the distribution of cardiac arrhythmias. Initially proposed a procedure electrocardiographic gating to compensate for errors inherent in the process of filtering segments. For the evaluation of distributions and determine which of the different encoding methods produces greater separation between different kinds of arrhythmias studied (AFIB, AFL, SVTA, VT, Normal's), use a function based on the dispersion of the elements on the centroid of its class, the result being that the best encoding for the entire system is through the method of threshold value for a ternary code with E = 1 / 12.

Abstact This paper proposes a hybrid vertex-centered finite volume/finite element method for solution of the two dimensional (2D) incompressible Navier-Stokes equations on unstructured grids. An incremental pressure fractional step method is adopted to handle the velocity-pressure coupling. The velocity and the pressure are collocated at the node of the vertex-centered control volume which is formed by joining the centroid of cells sharing the common vertex. For the temporal integration of the momentum equations, an implicit second-order scheme is utilized to enhance the computational stability and eliminate the time step limit due to the diffusion term. The momentum equations are discretized by the vertex-centered finite volume method (FVM) and the pressure Poisson equation is solved by t...

The purpose of this study is to present a framework for quantitative analysis of spinal curvature in 3D. In order to study the properties of such complex 3D structures, we propose two descriptors that capture the characteristics of spinal curvature in 3D. The descriptors are the geometric curvature (GC) and curvature angle (CA), which are independent of the orientation and size of spine anatomy. We demonstrate the two descriptors that characterize the spinal curvature in 3D on 30 computed tomography (CT) images of normal spine and on a scoliotic spine. The descriptors are determined from 3D vertebral body lines, which are obtained by two different methods. The first method is based on the least-squares technique that approximates the manually identified vertebra centroids, while the second method searches for vertebra centroids in an automated optimization scheme, based on computer-assisted image analysis. Polynomial functions of the fourth and fifth degree were used for the description of normal and scoliotic spinal curvature in 3D, respectively. The mean distance to vertebra centroids was 1.1 mm ({+-}0.6 mm) for the first and 2.1 mm ({+-}1.4 mm) for the second method. The distributions of GC and CA values were obtained along the 30 images of normal spine at each vertebral level and show that maximal thoracic kyphosis (TK), thoracolumbar junction (TJ) and maximal lumbar lordosis (LL) on average occur at T3/T4, T12/L1 and L4/L5, respectively. The main advantage of GC and CA is that the measurements are independent of the orientation and size of the spine, thus allowing objective intra- and inter-subject comparisons. The positions of maximal TK, TJ and maximal LL can be easily identified by observing the GC and CA distributions at different vertebral levels. The obtained courses of the GC and CA for the scoliotic spine were compared to the distributions of GC and CA for the normal spines. The significant difference in values indicates that the descriptors of GC and CA may be used to detect and quantify scoliotic spinal curvatures. The proposed framework may therefore improve the understanding of spine anatomy and aid in the clinical quantitative evaluation of spinal deformities.

Algorithms were developed for the extraction of two components of mean velocity, standard deviation, and the associated correlation coefficient from laser transit anemometry (LTA) data ensembles. The solution method is based on an assumed two-dimensional Gaussian probability density function (PDF) model of the flow field under investigation. The procedure consists of transforming the data ensembles from the data acquisition domain (consisting of time and angle information) to the velocity space domain (consisting of velocity component information). The mean velocity results are obtained from the data ensemble centroid. Through a least squares fitting of the transformed data to an ellipse representing the intersection of a plane with the PDF, the standard deviations and correlation coefficient are obtained. A data set simulation method is presented to test the data reduction process. Results of using the simulation system with a limited test matrix of input values is also given.

Abstract The structure of the Arctic stratospheric polar vortex in three chemistry-climate models (CCMs) taken from the CCMVal-2 intercomparison is examined using zonal mean and geometric-based methods. The geometric methods are employed by taking 2D moments of potential vorticity fields that are representative of the polar vortices in each of the models. This allows the vortex area, centroid location and ellipticity to be determined, as well as a measure of vortex filamentation. The first part of the study uses these diagnostics to examine how well the mean state, variability and extreme variability of the polar vortices are represented in CCMs compared to ERA-40 reanalysis data, and in particular for the UMUKCA-METO, NIWA-SOCOL and CCSR/NIES models. The second part of the study assesses ...

The charge division technique is a simple concept used in photon-counting imaging detectors to determine one or two-dimensional event coordinates by location of the centroid of the charge cloud generated in the detector. Traditional devices, such as the resistive anode and wedge-and-strip anode, utilize resistive and geometric methods respectively to implement this technique, enabling them to achieve reasonably good spatial resolution at moderate event rates using a low electronic channel count. We describe the Capacitive Division Image Readout (C-DIR), a simple method of implementing charge division readout with major performance advantages and which is simple and economical to construct. C-DIR utilizes three elements; (i) a resistive layer providing event charge localization and DC signa...

Centroid of a graph is a structure composed of nodes closest from all others. This suggests the idea of center of mass average of all edges, weighted by the local density or specific weight. Computing this centroid in a classic way needs a global view of the graph environment. In this paper, an algo...

In the title compound, [FeCl2(C18H12N2)], the FeII atom is four-coordinated in a distorted tetra­hedral arrangement by an N,N?-bidentate 2,2?-biquinoline ligand and two chloride ions. In the crystal, there are extensive ?–? contacts between the pyridine rings [centroid–centroid distances = 3.7611?(3...

In its crystal structure, the title compound, C9H7NO3, forms ?-stacked dimers, with a centroid–centroid distance of 3.475?(5)?Å between the benzenoid and the 2,4 dicarbonyl oxazine rings. These dimers then form staircase-like linear chains through further ?-stacking between the benzenoid rings [cent...

In the title compound, C12H14N2O2, the quinoxaline ring system and the C atoms of the methylene and methyl substituents lie on a mirror plane. The crystal packing is stabilized by weak ?–? inter­actions [centroid–centroid distance = 3.680?(7)?Å].

In the title compound, C14H9FN2, the dihedral angle between the benzene ring and the quinoxaline ring system is 22.2?(3)°. Any aromatic ?–? stacking in the crystal must be very weak, with a minimum centroid–centroid separation of 3.995?(2)?Å.

The title complex, [CuBr(C6H4NO3)(H2O)]n, exhibits a layered structure which is stabilized by inter­molecular O—H?O and O—H?Br? hydrogen bonds, van der Waals forces and ?–? inter­actions [centroid–centroid distance = 3.747(4)?Å] between the parallel pyridine rings from two neighboring layers.

The title mol­ecule, C18H19N3O3, lies on a mirror plane that bis­ects the adamantyl group. In the crystal, C—H?O and C—H?N inter­actions lead to supra­molecular chains along [100]. These assemble into layers in the ab plane via ?–? inter­actions [centroid–centroid distance = 3.6548?(7)?Å] between th...

In the title compound, [Pt(CH(3))(2)(C(18)H(15)As)(2)], the Pt(II) atom adopts a distorted cis-PtAs(2)C(2) square-planar coordination geometry. In the crystal, mol-ecules inter-act via aromatic ?-? stacking inter-actions [centroid-centroid separation = 3.6741?(18)?Å]. PMID:21579645

It is shown that the centroid of the heliospheric equator undergoes quasi-periodic oscillations. During the minimum of the 11-year cycle, the centroid shifts southwards (the so-called bashful-ballerina effect). The direction of the shift reverses during the solar maximum. The solar quadrupole is responsible for this effect. The shift is compared with the tilt of the heliospheric current sheet.

A new benzimidazole compound, C12H14N2O2, has been synthesized by the reaction of 2-methyl-1H-benzimidazole and ethyl 2-bromo­acetate. In the crystal structure, weak inter­molecular C—H?N hydrogen bonds link the mol­ecules into chains. ??? Contacts (centroid?centroid distance = 3.713?Å) are observed...

Fully automated prostate segmentation helps to address several problems in prostate cancer diagnosis and treatment: it can assist in objective evaluation of multiparametric MR imagery, provides a prostate contour for MR-ultrasound (or CT) image fusion for computer-assisted image-guided biopsy or therapy planning, may facilitate reporting and enables direct prostate volume calculation. Among the challenges in automated analysis of MR images of the prostate are the variations of overall image intensities across scanners, the presence of nonuniform multiplicative bias field within scans and differences in acquisition setup. Furthermore, images acquired with the presence of an endorectal coil suffer from localized high-intensity artifacts at the posterior part of the prostate. In this work, a three-dimensional method for fast automated prostate detection based on normalized gradient fields cross-correlation, insensitive to intensity variations and coil-induced artifacts, is presented and evaluated. The components of the method, offline template learning and the localization algorithm, are described in detail. The method was validated on a dataset of 522 T2-weighted MR images acquired at the National Cancer Institute, USA that was split in two halves for development and testing. In addition, second dataset of 29 MR exams from Centre d'Imagerie Médicale Tourville, France were used to test the algorithm. The 95% confidence intervals for the mean Euclidean distance between automatically and manually identified prostate centroids were 4.06 +/- 0.33 mm and 3.10 +/- 0.43 mm for the first and second test datasets respectively. Moreover, the algorithm provided the centroid within the true prostate volume in 100% of images from both datasets. Obtained results demonstrate high utility of the detection method for a fully automated prostate segmentation.

We investigate 35 pre-stellar cores and 36 proto-stellar cores in the Perseus molecular cloud. We find a very tight correlation between the physical parameters describing the N2H+ and NH3 gas. Both the velocity centroids and the line widths of N2H+ and NH3 correlate much better than either species correlates with CO, as expected if the nitrogen-bearing species are probing primarily the dense core gas where the CO has been depleted. We also find a tight correlation in the inferred abundance ratio between N2H+ and para-NH3 across all cores, with N(p-NH3)/N(N2H+)= 22 +/- 10. We find a mild correlation between NH3 (and N2H+) column density and the (sub)millimeter dust continuum derived H2 column density for pre-stellar cores, N(p-NH3)/N(H2) ~ 10e-8, but do not find a fixed ratio for proto-stellar cores. The observations suggest that in the Perseus molecular cloud the formation and destruction mechanisms for the two nitrogen-bearing species are similar, regardless of the physical conditions in the dense core gas. ...

In the present study, the optimized mixture proportions of low cholesterol-low fat mayonnaise contained soy milk as an egg yolk substitute (10%) with different composition of xanthan gum (XG), guar gum (GG) and mono- & diglycerides emulsifier (MDG) (0-0.36% of each component) were determined by applying the simplex-centroid mixture design method to achieve the desired stability, textural and rheological properties and sensory characteristics for effective formulation process. Results revealed that the best mixture was the formulation contained 6.7% mono- & diglycerides, 36.7% guar gum and 56.7% xanthan gum. The xanthan gum was the component showing the highest effect on all the properties of mayonnaise samples. In addition, an increase of xanthan gum followed by guar gum caused greater val...

  A new technique of two dimensional mold filling simulation based on the Direct Finite Difference Method has been developed. Non-orthogonal elements can be employed in this technique so that the original complicated and thin shape of a casting, including the gating system, can be retained in its simulation model. Pressure points are located at each centroid of the rectangular element while fluid velocity vectors are at vertexes which are the representative points of nodal regions formed around the vertexes. The momentum equation is discretized in each nodal region while the mass conservation equation is discretized in element. Two dimensionless parameters ??, ?s are defined to predict the free surface movement more accurately and mass conservation in the free surface regions is solved explicitly by using these parameters. Some numerical mold filling examples, namely die casting of a disk-like cavity and gravity casting of a curved gating system, showed promising results of the proposed technique.   

PurposeTo evaluate implanted markers as a surrogate for tumor-based setup during image-guided lung cancer radiotherapy with audiovisual biofeedback. Methods and MaterialsSeven patients with locally advanced non-small-cell lung cancer were implanted bronchoscopically with gold coils. Markers, tumor, and a reference bony structure (vertebra) were contoured for all 10 phases of the four-dimensional respiration-correlated fan-beam computed tomography and weekly four-dimensional cone-beam computed tomography. ResultsThe systematic/random interfractional marker-to-tumor centroid displacements were 2/3, 2/2, and 3/3 mm in the x (lateral), y (anterior-posterior), and z (superior-inferior) directions, respectively. The systematic/random interfractional marker-to-bone displacements were 2/3, 2/3, an...

According to the FLIR image of complex ground fixed target have disordered gray difference between target and background, and no base image available, we propose a target detection algorithm in FLIR imagery using scale space theory. First the reference image been created depending on the satellite dates, 2D Forward-looking image sequences of target regions created by using VRMap software according to the flying route. After performing LoG filtering on these reference images, we obtain a series of characteristic scale, where each scale is related to the size of target. Using these scales, several blob-like candidate regions can be found with the same size with reference image. Then the result is obtained between candidate regions and the reference image using Hausdorff measure and centroid distance. A simulation experiment is developed for the proposed algorithm and results show that our method has high accuracy and quickly performance and it has strong practicability.

The motion of single- and two-cavitation bubbles generated by laser beams directly beneath a free surface is studied experimentally, using high-speed photography, and theoretically using the highly accurate boundary integral method. Favorable comparisons of bubble shape history and centroid motion are observed while the numerical calculations provide information on the pressure field surrounding the bubbles. A range of responses, including the null impulse state, is obtained for the two bubbles depending on the bubble size ratio and the interbubble and bubble-free surface distances, although in all cases reported in this article, the bubble nearest the free surface yields a high-speed liquid jet directed away from the free surface. It is also found that when the free-surface{endash}bubble interaction is strong, a fast free-surface spike is formed for both the single- and two-bubble cases. {copyright} 2001 American Institute of Physics.

Microarrays are made it possible to simultaneously monitor the expression profiles of thousands of genes under various experimental conditions. It is used to identify the co-expressed genes in specific cells or tissues that are actively used to make proteins. This method is used to analysis the gene expression, an important task in bioinformatics research. Cluster analysis of gene expression data has proved to be a useful tool for identifying co-expressed genes, biologically relevant groupings of genes and samples. In this paper we applied K-Means with Automatic Generations of Merge Factor for ISODATA- AGMFI. Though AGMFI has been applied for clustering of Gene Expression Data, this proposed Enhanced Automatic Generations of Merge Factor for ISODATA- EAGMFI Algorithms overcome the drawbacks of AGMFI in terms of specifying the optimal number of clusters and initialization of good cluster centroids. Experimental results on Gene Expression Data show that the proposed EAGMFI algorithms could identify compact clus...

The geothermal structure beneath of the Barramiya?Red Sea coast area of the Central Eastern Desert of Egypt has been determined using Curie point depth (CPD), which is temperature-dependent. The CPD and the surface heat flow (q) maps of such area are estimated by analyzing aeromagnetic data. Such data are low-pass-filtered and analyzed to estimate the magnetic bottom using the centroid method. The heat flow map reflects the geothermic nature of the region. However, it is suggested that the shallow Curie point temperature depth pattern depends on the tectonic regime and morphology, which continues eastwards through the Red Sea. Particularly, the coastal regions are characterized by high heat flow (83.6?mW/m2) and shallow Curie depth (22.5?km), whereas the western portion of the studied area...

This is part two of a series on the optical modeling activities for JWST. Starting with the linear optical model discussed in part one, we develop centroid and wavefront error sensitivities for the special case of a segmented optical system such as JWST, where the primary mirror consists of 18 individual segments. Our approach extends standard sensitivity matrix methods used for systems consisting of monolithic optics, where the image motion is approximated by averaging ray coordinates at the image and residual wavefront error is determined with global tip/tilt removed. We develop an exact formulation using the linear optical model, and extend it to cover multiple field points for performance prediction at each instrument aboard JWST. This optical model is then driven by thermal and dynamic structural perturbations in an integrated modeling environment. Results are presented.

We have operated a Medipix2 CMOS readout chip, with amplifying, shaping and charge discriminating front-end electronics integrated on the pixel level, as a highly segmented direct charge collecting anode in a Three-Stage Gas Electron Multiplier (Triple-GEM) to detect the ionization from {sup 55}Fe X-rays and electrons from {sup 106}Ru. The device allows to perform moderate energy spectroscopy measurements (20% FWHM at 5.9keV X-rays) using only digital readout and two discriminator thresholds. Being a truly 2D detector, it allows to observe individual clusters of minimum ionizing charged particles in Ar/CO{sub 2} (70:30) and He/CO{sub 2} (70:30) mixtures and to achieve excellent spatial resolution for position reconstruction of primary clusters down to {approx}50{mu}m, based on the binary centroid determination method.

A localization algorithm for ultrasonic robot described is based on range readings from wide beam ultrasonic transducers to built a model of the empty regions in the room. The method is incorporated into a move-to-station behavior which was demonstrated on the Georgia Tech mobile robot. A belief model of the range of readings that was based on Dempster-Shafer theory was used to compute the belief of points in the environment being empty, occupied, or unknown. The current belief in the empty space was used to construct a weighted centroid of the empty space after each move of the robot. By moving toward this center of mass and continually adding to the beliefs of the point in the environment the robot iteratively moved to the center of the open space.

Clustering XML documents is extensively used to organize large collections of XML documents in groups that are coherent according to structure and/or content features. The growing availability of distributed XML sources and the variety of high-demand environments raise the need for clustering approaches that can exploit distributed processing techniques. Nevertheless, existing methods for clustering XML documents are designed to work in a centralized way. In this paper, we address the problem of clustering XML documents in a collaborative distributed framework. XML documents are first decomposed based on semantically cohesive subtrees, then modeled as transactional data that embed both XML structure and content information. The proposed clustering framework employs a centroid-based partiti...

We demonstrate subcentimeter depth profiling at a stand off distance of 330 m using a time-of-flight approach based on time-correlated single-photon counting. For the first time to our knowledge, the photon-counting time-of-flight technique was demonstrated at a wavelength of 1550 nm using a superconducting nanowire single-photon detector. The performance achieved suggests that a system using superconducting detectors has the potential for low-light-level and eye-safe operation. The system's instrumental response was 70 ps full width at half-maximum, which meant that 1 cm surface-to-surface resolution could be achieved by locating the centroids of each return signal. A depth resolution of 4 mm was achieved by employing an optimized signal-processing algorithm based on a reversible jump Markov chain Monte Carlo method.

A method and apparatus for determining centroid channel locations is disclosed for use in a system activated by one or more multichannel plates (16,18) and including a linear diode array (24) providing channels of information 1, 2, . . . , n, . . . , N containing signal amplitudes A.sub.n. A source of analog A.sub.n signals (40), and a source of digital clock signals n (48), are provided. Non-zero A.sub.n values are detected in a discriminator (42). A digital signal representing p, the value of n immediately preceding that whereat A.sub.n takes its first non-zero value, is generated in a scaler (50). The analog A.sub.n signals are converted to digital in an analog to digital converter (44). The digital A.sub.n signals are added to produce a digital .SIGMA.A.sub.n signal in a full adder (46). Digital 1, 2, . . . , m signals representing the number of non-zero A.sub.n are produced by a discriminator pulse counter (52). Digital signals representing 1 A.sub.p+ 1, 2 A.sub.p+2, . . . , m A.sub.p+m are produced by pairwise multiplication in multiplier (54). These signals are added in multiplier summer (56) to produce a digital .SIGMA.nA.sub.n -p.SIGMA.A.sub.n signal. This signal is divided by the digital .SIGMA.A.sub.n signal in divider (58) to provide a digital (.SIGMA.nA.sub.n /.SIGMA.A.sub.n) -p signal. Finally, this last signal is added to the digital p signal in an offset summer (60) to provide .SIGMA.nA.sub.n /.SIGMA.A.sub.n, the centroid channel locations.

One of the precise widely used global Zenith Hydrostatic Delay (ZHD) model is based on the gravity value at the centroid of the atmospheric column at the station of observation and gravity value at the centroid is constant in this model for a specific location throughout the year. However, as the content and extent of atmosphere varies temporally, its centroid and consequently gravity value at the centroid also varies. Apart from this, the actual atmospheric condition of different region is not alike. Therefore, there is a need to develop a regional mean gravity model and development of such model has been discussed in this paper. To obtain the mean gravity model, first a regional model of centroid height of atmospheric column was developed as a function of the surface pressure and temperature. It was developed by multiple regressions between estimated centroid of the atmosphere and surface pressure, surface temperature using radiosonde data of five radiosonde stations spread over the Indian subcontinent. Three years radiosonde data from 2006 to 2008 was used for each station. The root mean square error in estimating centroid of the atmospheric column is about ±326 m, which is negligible considering the variability of the atmosphere and its content. The centroid height model has been used to formulate the mean gravity model, considering uniform lapse rate in gravity with height. It is found that proposed mean gravity model provides temporal variation of mean gravity values at the centroid and thus matches with the reality. The interesting advantage of the developed model is that the model shows diurnal variation of mean gravity. The accuracy of ZHD has shown of the order of about 0.3 mm using the developed regional mean gravity model. However, already developed ZHD model has shown a slight inferior result compared to the developed model. These models have shown accuracy of about 0.8 mm and 0.6 mm.

In the title compound, C17H12O4, the six-membered heterocyclic ring adopts a distorted screw-boat conformation. The mol­ecular structure exhibits an S(6) ring motif, owing to an intra­molecular O—H?O hydrogen bond. In the crystal, weak C—H?O contacts generate an infinite chain along the c axis. There are also ?–? stacking inter­actions between neighbouring isochromanedione benzene rings, with a centroid–centroid distance of 3.755?(1)?Å, and C—O?? inter­actions with an O?centroid distance of 3.964?(2)?Å. PMID:1708086

Cell motility and migration are central to the development and maintenance of multicellular organisms, and errors during this process can lead to major diseases. Consequently, the mechanisms and phenomenology of cell motility are currently under intense study. In recent years, a new interdisciplinary field focusing on the study of biological processes at the nanoscale level, with a range of technological applications in medicine and biological research, has emerged. The work presented in this thesis is at the interface of cell biology, image processing, and stochastic modeling. The stochastic models introduced here are based on persistent random motion, which I apply to real-life studies of cell motility on flat and nanostructured surfaces. These models aim to predict the time-dependent position of cell centroids in a stochastic manner, and conversely determine directly from experimental recordings of cell motility the various motility parameters. This can aid the experimentalist to draw biologically relevant conclusions about cell-substrate interactions. The need to track cells in a large number of movies has raised the question of automation of cell tracking and that of reproducibility and robustness of cell centroid measurement. To address this, I wrote the PACT cell tracking program, which is optimized for uniform as well as non-uniform backgrounds such as nanostructured surfaces. Rapid progress in the field of the automation of cell tracking steered us into a comparative study of PACT’s performance against other cell tracking programs. We find that different programs yield somewhat different results when applied to the same movie of migrating cells but that the differences are not statistically significant. To introduce persistent random motion, I first present a study of idealized random motion in two dimensions. This finds direct application to experimental studies of cell membrane fluidity and membrane protein dynamics, and I improve on the methodology currently used in that field by showing how to assess the randomness of the motility and how to optimally determine the diffusion coefficient. By adding a persistence component to simple random motion I introduce the standard Ornstein-Uhlenbeck process. I build on this commonly used cell motility model to address the challenges of working with real-life data: positional (centroid coordinate measuring) error and time discretization (due to finite frame rate in a movie of motile cells). This includes optimally measuring the motility parameters and balancing precision of measurement against the mathematical complexity of real-life models of cell motility. Finally, I expanded our understanding of cell response to surface topography by generalizing the Orstein-Uhlenbeck process to study cell motility on anisotropic substrates. I apply the general model to analyze cell motility on a series of anisotropic substrates and discuss the implications of our observations. This work is potentially useful to cell biologists by addressing theirneed for precise yet simple tools for studies of cell motility. The advances in the theoretical understanding of motility presented here bear the experimentalists’ needs in mind, and can find direct technological applications such as cell guidance and growth using nanotopography.

The Draco dwarf spheroidal galaxy (dSph), with its apparent immense mass to light ratio and compact size, holds many clues to the nature of the enigmatic dark matter. Here we present deep photometric studies of this dwarf galaxy, undertaken with the MegaCam Camera at the Canada-France-hawaii Telescope, the Wide Field Camera at the Isaac Newton Telescope and the Wide-Field and Planetary Camera on board the Hubble Space Telescope. The new photometric data cover the entirety of the galaxy, and reach i=24.5 at 50% completeness, significantly deeper than previous panoramic studies, allowing searches for tidal disturbances of much lower surface brightness than has been possible before. With these improved statistics, we find no evidence for asymmetric disturbances or tidal tails that possess more than 3% of the stars found within the centre of the galaxy. We find that the central stellar density, as probed by the HST data, rises into the central 0.5'. Uncertainties in the position of the centroid of the galaxy do n...

We have developed a new fast simulator that takes as inputs cloud fields from a general circulation model (GCM) or profiles of optical extinction from CloudSat/MODIS on NASA's A-train satellites and produces an estimate of the cloud optical centroid pressure (OCP). The OCP is a parameter commonly used in trace-gas retrieval algorithms to account for photon-pathlength variations produced by clouds and aerosol. It also provides information about cloud vertical structure that is different from the cloud-top pressure; it is more sensitive to the mean solar photon-penetration depth. There are two algorithms that estimate cloud optical centroid cloud pressure from the Ozone Monitoring Instrument (OMI) on the NASA Aura satellite. One approach makes use of the filling-in of solar Fraunhofer lines due to rotational-Raman scattering at ultraviolet wavelengths and the other uses oxygen dimer absorption near 477 nm. We have compared our fast simulator results with those from a more exact radiative transfer simulation of the OMI rotational-Raman cloud OCP based on CloudSat optical extinction profiles. The results show that the fast simulator performs well for OMI cloud OCP retrievals. We then use the fast simulator with CloudSat/MODIS data to do a detailed comparison with collocated OMI cloud OCP retrievals from both OMI cloud OCP algorithms in order to assess the performance of these retrievals under a wide range of conditions. We find generally good agreement between OMI cloud OCPs and those predicted by CloudSat at moderate to high effective cloud fractions. However, some differences are apparent. These differences may be attributed to several factors including undetected snow and ice, cloud 3D effects, representativeness (collocation) error, and systematic differences between the OMI visible and UV retrievals and the extinction profiles derived from the CloudSat millimeter cloud radar in conjunction with MODIS radiances. We find that both OMI cloud algorithms produce very similar results. Because the two OMI algorithms are completely independent (based on different physical principles and measurements made with 2 separate detectors), differences are not likely due to OMI measurement or retrieval errors.

We characterize certain maps by their action on a fixed polynomial in noncommuting variables on algebras satisfying certain d -freeness condition. Consequently, a characterization of the centroid of a prime ring is obtained.

The title compound, C(4)H(8)N(5) (+)·C(2)HO(4) (-), was obtained from the reaction of oxalic acid and 2,4-diamino-6-methyl-1,3,5-triazine. The protonated triazine ring is essentially planar with a maximum deviation of 0.035?(1)?Å, but the hydrogen oxalate anion is less planar, with a maximum deviation of 0.131?(1)?Å for both carbonyl O atoms. In the crystal, the ions are linked by inter-molecular N-H?O, N-H?N, O-H?O and C-H?O hydrogen bonds, forming a three-dimensional network. Weak ?-? [centroid-centroid distance = 3.763?Å] and C-O?? inter-actions [O?centroid = 3.5300?(16)?Å, C-O?centroid = 132.19?(10)°] are also present. PMID:22590348

A new Constellation-X Centroid Detector Assembly (CDA) was completed and delivered by .... Work had been preceding at GSFC along a parallel path using a concept involving ..... Integral Workshop {The Extreme ... ApL \\&C 39, 465 (1 999) ...

calibration requirement specifies the alignment of certain instrument pointing frames to an ... The IRS instrument includes peak-up arrays to provide real-time centroids of .... and R.V.F. Lopes, “Parameter interference in distortion and alignment ...

This patent describes an optical beam position controller in which a video camera captures an image of the beam in its video frames, and conveys those images to a processing board which calculates the centroid coordinates for the image. The image coordinates are used by motor controllers and stepper motors to position the beam in a predetermined alignment. In one embodiment, system noise, used in conjunction with Bernoulli trials, yields higher resolution centroid coordinates.

In the title compound, C13H10OS, the phenyl rings are inclined to one another by 51.12?(8)°. There is a short C—H?S contact in the molecule.In the crystal, molecules are linked via C—H?O hydrogen bonds forming chains along the a axis. Molecules are also linked by C—H?? and weak ?–? interactions [centroid–centroid distance = 3.9543?(10)?Å].

Using metal-oxide-semiconductor (MOS) structures, the shift of centroid (peak) of {gamma}-ray energy distributions emitted from positron annihilation has been measured as a function of incident positron energy. The Doppler centroid shift was found to be consistent with the positron motion in the MOS depletion region. The results are described by a one-dimensional positron diffusion model, and provide information on effective'' positron diffusion length under applied field.

In the title mol­ecule, C12H12N4O3S, there is an intra­molecular O—H?N hydrogen bond. The dihedral angle between the benzene and triazine rings is 65.9?(3)°. In the crystal, N—H?S and O—H?N hydrogen bonds link the mol­ecules into chains along [010]. In addition, there are weak ?–? stacking inter­actions between symmetry-related triazine rings with a centroid–centroid distance of 3.560?(3)°.

In the crystal of the title compound, C(15)H(8)N(4)O(6), the mol-ecules are organized in layers due to their linkage by weak C-H?N hydrogen bonds. The layers are themselves inter-connected by weak C-H?O hydrogen bonds and ?-? inter-actions [centroid-centroid distances = 3.8690?(15) and 3.9017?(16)?Å]. The dihedral angle between the rings is 31.9?(1)°. PMID:21587662

In the title compound, C11H11N3O4, the 3,5-dioxopiperazine ring adopts an envelope conformation, with the N atom connecting to the –CH2COOH group on the flap. In the crystal, mol­ecules are linked by O—H?N hydrogen bonds to produce a linear chain running along the c axis. ?–? stacking is observed between parallel pyridine rings of adjacent mol­ecules, the centroid–centroid distance being 3.834?(2)?Å.

In the title compound, C(19)H(17)NO(2), the piperidine ring adopts a chair conformation. The mean planes of the piperidine ring and the anthracene ring system are inclined at a dihedral angle of 38.7?(1)°. In the crystal, adjacent mol-ecules are linked through C-H?? and ?-? [centroid-centroid distance = 3.782?(1)?Å] inter-actions, forming a layer parallel to the bc plane. PMID:23125677

In the title compound, C19H12BrFO3S, the 3-fluoro­phenyl ring makes a dihedral angle of 80.85?(5)° with the mean plane [r.m.s. deviation = 0.009?(2)Å] of the naphtho­furan fragment. In the crystal, mol­ecules are linked by slipped ?–? inter­actions between the furan and the outer benzene rings of neighbouring mol­ecules [centroid–centroid distance = 3.756?(3)?Å and slippage of 1.189?(3)?Å].

In the title compound, [Zr(C5H5)(C13H9)2Cl]·C7H8, the ZrIV atom is coordinated by a Cl atom, a cyclo­penta­dienyl (Cp) ligand [Zr–centroid (Cp) = 2.199?(3)?Å] and two fluorenyl ligands (Fl) [Zr–centroid (Fl) = 2.273?(2)?Å and Zr—CH from fluorenyl = 2.355?(2)?Å] in a distorted tetra­gonal geometry. T...

The title mol-ecule, C(18)H(19)N(3)O(3), lies on a mirror plane that bis-ects the adamantyl group. In the crystal, C-H?O and C-H?N inter-actions lead to supra-molecular chains along [100]. These assemble into layers in the ab plane via ?-? inter-actions [centroid-centroid distance = 3.6548?(7)?Å] between the oxadiazole and benzene rings. PMID:22412666

In the title compound, C15H12N4·H2O, the organic mol­ecule displays approximate non-crystallographic twofold symmetry: the dihedral angle between the benzimidazole ring systems is 81.37?(12)°. In the crystal, the components are linked by O—H?N hydrogen bonds, forming chains propagating in [101]. Aromatic ?–? stacking [centroid–centroid separation = 3.595?(2)?Å] helps to consolidate the structure.

In the title compound, [Cd2I4(C24H22N4)2], the 1,3-bis­[(2-methyl-1H-benzimidazol-1-yl)meth­yl]benzene ligand bridges two CdI2 units, forming a centrosymmetric dinuclear complex. The CdII atom adopts a distorted tetra­hedral coordination geometry. In the crystal, complex mol­ecules are linked into columns parallel to [101] by ?–? stacking inter­actions, with centroid–centroid distances of 3.558?(2)?Å.

The measured distance between two stars on a single Spitzer Space Telescope Infrared Array Camera (IRAC) Channel 1 (Ch1) BCD image can be systematically off by as much as one-fifth of a pixel which is 0.24 arcsec on the sky -- if standard intensity-weighted mean centroids are calculated (Mighell, Glaccum, & Hoffman 2008). The square centroid error distribution is well modeled by using a Point Spread Function (PSF) described by a diffraction-limited Airy pattern at 3.6 microns with a 60 percent circular central obscuration. This simple model describes (1) the separability of the centroid errors in the X and Y direction, (2) the size (amplitude) of the maximum centroid errors in X and Y, and (3) the shape (nearly sinusoidal) and (almost) the phase of the separable centroid errors as a function of X and Y pixel phase. The primary physical cause of the square centroid error distribution is that the space-based nearly-diffraction-limited PSF of the IRAC Ch1 PSF was strongly undersampled at the focal plane of the IRAC Ch1 camera by its detector array. This work has been supported by a grant from the National Aeronautics and Space Administration (NASA), NNX10AD45G, which was awarded by the Astrophysics Data Analysis Program (ADAP) of NASA's Science Mission Directorate.

The seismic activity that affects the Portuguese territory occurs mainly and more frequently offshore, in the south and southwest of Mainland Portugal. The study of the Portuguese seismicity is conditioned by the poor azimuthal coverage, due to the geographic location of Portugal, and by the large sedimentary basin west of the straight of Gibraltar (Cadiz Basin). In this work we focus on the study of regional seismicity in Portugal (mostly offshore earthquakes) using a recently developed package - the KIWI (Kinematic Waveform Inversion) tools. This new technique performs point and finite source inversions at regional distances. The KIWI routine is a multi-step approach composed of 3 steps, finding different source parameters at different steps. At first, we assume a point source approximation. We initially retrieve the focal mechanism of the earthquake (strike, dip, and rake), the seismic scalar moment M0 and the depth. This inversion step is performed in the spectral domain, by fitting amplitude spectra. In the second step, compressive and dilatation quadrants are retrieved, which is carried out in the time domain. Refined latitude and longitude for the centroid, as well as an earthquake origin time, are also given at this time. The final step of the inversion consists of a simplified finite-fault inversion. We assume the eikonal source model, and determine parameters such as the fault plane orientation (discrimination between fault and auxiliary plane), radius (rupture extension), nucleation point coordinates (indicative of directivity effects) and average rupture velocity of the earthquake. This inversion is performed in the frequency domain by fitting amplitude spectra in a wider frequency band (including higher frequencies). This multi-step approach has the advantage of using different inversion methods, seismic phases and range of frequencies to infer specific parameters. In this work we study 17 regional earthquakes occurred in Southwest Iberia between 2007 and 2009 with moderate magnitude (3.3 to 4.4). The small magnitude of these earthquakes prevents their study with the third step of the algorithm. The solutions obtained are evaluated by a quality criteria and compared with other moment tensor solutions. The quality factor is based on the number of stations and on the misfit between the recorded and the synthetic waveforms. Apart from this study another offshore event was analyzed. The earthquake occurred SW of St Vincent Cape on February 12, 2007 with Mw 5.9. In this study the KIWI tools were employed to infer both the point and finite source parameters of this earthquake. The results of the kinematic source inversion step indicate that the 2007 HAP earthquake ruptured a plane trending WNW-ESE, whereas previous studies suggest that the conjugate fault plane (ENE-WSW) is the true rupture plane. The proposed solution also indicates that the earthquake occurred within the SWIM fault-zone. However, the 46° dip is difficult to reconcile with the sub-vertical nature of the SWIM faults.

A compact optoelectronic sensor unit measures the apparent motion of the Sun across the sky. The data acquired by this chip are processed in an external processor to estimate the relative orientation of the axis of rotation of the Earth. Hence, the combination of this chip and the external processor finds the direction of true North relative to the chip: in other words, the combination acts as a solar compass. If the compass is further combined with a clock, then the combination can be used to establish a threeaxis inertial coordinate system. If, in addition, an auxiliary sensor measures the local vertical direction, then the resulting system can determine the geographic position. This chip and the software used in the processor are based mostly on the same design and operation as those of the unit described in Micro Sun Sensor for Spacecraft (NPO-30867) elsewhere in this issue of NASA Tech Briefs. Like the unit described in that article, this unit includes a small multiple-pinhole camera comprising a micromachined mask containing a rectangular array of microscopic pinholes mounted a short distance in front of an image detector of the active-pixel sensor (APS) type (see figure). Further as in the other unit, the digitized output of the APS in this chip is processed to compute the centroids of the pinhole Sun images on the APS. Then the direction to the Sun, relative to the compass chip, is computed from the positions of the centroids (just like a sundial). In the operation of this chip, one is interested not only in the instantaneous direction to the Sun but also in the apparent path traced out by the direction to the Sun as a result of rotation of the Earth during an observation interval (during which the Sun sensor must remain stationary with respect to the Earth). The apparent path of the Sun across the sky is projected on a sphere. The axis of rotation of the Earth lies at the center of the projected circle on the sphere surface. Hence, true North (not magnetic North), relative to the chip, can be estimated from paths of the Sun images across the APS. In a test, this solar compass has been found to yield a coarse estimate of the North (within tens of degrees) in an observation time of about ten minutes. As expected, the accuracy was found to increase with observation time: after a few hours, the estimated direction of the rotation axis becomes accurate to within a small fraction of a degree.

Abstract in portuguese O presente trabalho faz parte do programa GEOSAFRAS, estimativa e safras no Brasil, coordenado pela Companhia Nacional de Abastecimento e do Programa das Nações Unidas para o Desenvolvimento. Uma aplicação muito comum no gerenciamento de safras é o monitoramento de mudanças nos campos de cultivo usando imagens de satélite adquiridas em diferentes datas. Para isto, a compatibilidade espacial entre essas imagens é um requisito básico, mais ainda quando se trata de (more) imagens de diferentes sensores. Nesse artigo é descrita uma metodologia para a semi-automação do processo de correção geométrica com a finalidade de facilitar o ajuste geométrico entre imagens de diferentes sensores. Inicialmente, uma imagem base é manualmente corrigida a partir de dados extraídos de uma carta topográfica digital. Após essa correção, a imagem corrigida é utilizada como elemento base de referência para corrigir as outras imagens (denominadas neste trabalho de imagens de ajuste), as quais são adquiridas em datas diferentes e/ou de diferentes sensores. Depois de corrigida a imagem base todas as imagens (base e de ajuste) são segmentadas e classificadas. Os segmentos classificados como vegetação florestal são escolhidos para compor a malha relacional. As imagens de ajuste são registradas pelo processo imagem-imagem usando os centróides dos segmentos de vegetação florestal. Os segmentos de vegetação florestal presentes na imagem base são confrontados com os segmentos correspondentes nas imagens de ajuste, para buscar correspondências (matching). O processo de matching é realizado através da aplicação de algoritmos genéticos. Ao obter um resultado satisfatório na busca de correspondência, calcula-se os centróides correspondentes aos segmentos detectados, os quais são utilizados como pontos de controle para o processo de registro das imagens. Os resultados mostram que os algoritmos genéticos encontraram a solução ótima na maior parte dos experimentos realizados. Porém, para a imagem LANDSAT 2002 reamostrada a solução encontrada foi sub-ótima, pois um segmento sofreu grandes variações em relação ao mesmo segmento na imagem base. Abstract in english This work is part of the GEOSAFRAS program - estimates and harvests in Brazil - which is coordinated by the National Company of Supply and the United Nations Development Programme. A regular use in the management of harvests is the monitoring of the cultivation fields changes by using satellite images obtained at different dates. For this purpose, the spatial compatibility between these images is a necessary condition, even more when it comes to images from different sens (more) ors. This article describes a methodology for the semi-automation of the geometric rectification process aimed at facilitating the geometric adjustment between images from different sensors. First, a base image is manually rectified from data extracted from a digital topographic map. After such rectification, the correct image is used as a reference element to rectify other images (in this work, called adjustment images), which are acquired at other dates and/or from other sensors. Once the base image is rectified, all images (base and adjustment ones) are segmented and classified. The segments classified as forest vegetation are selected to compose the relational mesh. The adjustment images are registered by the image-image process by means of the forest vegetation segment centroids. The forest vegetation segments in the base image are compared to the corresponding segments in the adjustment images, to find pattern matching. The matching process involves the application of genetic algorithms. After obtaining a positive result regarding the pattern matching, the centroids corresponding to the detected segments are calculated; These centroids are used as control points for the image registry process. The results show that genetic algorithms have found the optimal solution in most experiments. However, regarding the LANDSAT 2002 resampled image, the solution found was sub-optimal because one of the segments showed large variations in relation to the same segment of the base image.

Statistics of the weak lensing of galaxies can be used to constrain cosmology if the galaxy shear can be estimated accurately. In general this requires accurate modelling of unlensed galaxy shapes and the point spread function (PSF). I discuss suboptimal but potentially robust methods for estimating galaxy shear by stacking images such that the stacked image distribution is closely Gaussian by the central limit theorem. The shear can then be determined by radial fitting, requiring only an accurate model of the PSF rather than also needing to model each galaxy accurately. When noise is significant asymmetric errors in the centroid must be corrected, but the method may ultimately be able to give accurate un-biased results when there is a high galaxy density with constant shear. It provides a useful baseline for more optimal methods, and a test-case for estimating biases. I test stacking methods on the simple toy simulations with constant PSF and shear provided by the GREAT08 project, on which most other existin...

This paper proposes a hybrid vertex-centered finite volume/finite element method for solution of the two dimensional (2D) incompressible Navier-Stokes equations on unstructured grids. An incremental pressure fractional step method is adopted to handle the velocity-pressure coupling. The velocity and the pressure are collocated at the node of the vertex-centered control volume which is formed by joining the centroid of cells sharing the common vertex. For the temporal integration of the momentum equations, an implicit second-order scheme is utilized to enhance the computational stability and eliminate the time step limit due to the diffusion term. The momentum equations are discretized by the vertex-centered finite volume method (FVM) and the pressure Poisson equation is solved by the Galerkin finite element method (FEM). The momentum interpolation is used to damp out the spurious pressure wiggles. The test case with analytical solutions demonstrates second-order accuracy of the current hybrid scheme in time and space for both velocity and pressure. The classic test cases, the lid-driven cavity flow, the skew cavity flow and the backward-facing step flow, show that numerical results are in good agreement with the published benchmark solutions.

We present VLA H I imaging data for a field in the NW of the galaxy cluster Abell 1367 (z = 0.02) in an attempt to probe the effect environment has on the interstellar medium of late-type spiral galaxies. Several galaxies show pronounced tails and asymmetries, and 7 out of 10 show significant, several kpc offsets between the HI centroid and the optical. We compare our results against a sample of optically bright, late-type galaxies (spirals) across the central 1.5 Mpc of the cluster taken from the Arecibo Galaxy Environment Survey (AGES). We calculate the H I deficiency and find that the expected global trend for the H I deficiency of these spirals to increase with projected proximity to the cluster core, seen in clusters like Coma and Virgo, is not observed. We classified the spirals into four evolutionary states, with the galaxies in each state sharing a similar degree of H I deficiency and optical colour. The common characteristics of the spirals in each evolutionary state suggests they have been subject t...

We use broadband optical imaging and Chandra X-ray data for a sample of 47 cluster central dominant galaxies (CDGs) to investigate the connection between star formation, the intracluster medium (ICM), and the central active galactic nucleus (AGN). By comparing the near-UV color gradients to the X-ray-derived properties on similar spatial scales, we find that a CDG is likely to experience significant star formation when: 1) the X-ray and galaxy centroids are within ~ 20 kpc of each other, 2) the central cooling time of the hot atmosphere is much less than ~ 8x10^8 yr (or has an entropy of less than ~ 30 keV cm^2), and 3) the ratio of jet (cavity) power to X-ray cooling luminosity is approximately less than unity. These conditions, in addition to the high ratio of cooling time to AGN outburst (cavity) age across our sample, are consistent with the idea that cooling and star formation at the centers of cooling flows are regulated by AGN feedback. Our results provide compelling evidence for a cycle of cooling, st...

We compare high-resolution ultraviolet spectra of the Sun and thirteen solarmass main sequence stars with different rotational periods that serve as proxies for their different ages and magnetic field structures. In this the second paper in the series, we study the dependence of ultraviolet emission-line centroid velocities on stellar rotation period, as rotation rates decrease from that of the Pleiades star HII314 (Prot = 1.47 days) to Alpha Cen A (Prot = 28 days). Our stellar sample of F9 V to G5 V stars consists of six stars observed with the Cosmic Origins 1Guest Observer, NASA/ESA Hubble Space Telescope and User of the Data Archive at the Space Telescope Science Institute. Spectrograph on HST and eight stars observed with the Space Telescope Imaging Spectrograph on HST. We find a systematic trend of increasing redshift with more rapid rotation (decreasing rotation period) that is similar to the increase in line red shift between quiet and plage regions on the Sun. The fastest-rotating solar-mass star in ...

We present the preliminary results of our astrometric study of stellar motions along the lines of sight of the Magellanic Clouds and the Galactic bulge. We find that we are able to select stars with proper motions as small as 0.03 inch/yr from five years of PSF photometry due to the characteristic nature of the shapes the light curves of HFM stars. This shape arises from the proper motion of the object relative to the initial fixed centroid location where all photometry of the object is performed. By selecting such light curves and performing astrometry on candidate HPM stars we have discovered 154 new high proper motion (HPM) stars in 50{sup {open_square}}{sup o} from amongst the {approx} 55 million of stars observed by the MACHO project in these fields. These objects have proper motions as high as 0.5 inch/yr, luminosities ranging from V {approx} 13 to V {approx} 19, and V-R colours between 0.3 and 1.45.

The FastTracKer (FTK) is a dedicated hardware system able to perform online fast and precise track reconstruction of the full events at the Atlas experiment, within an average latency of few dozens of microseconds. It is made of two pipelined processors: the Associative Memory (AM), finding low precision tracks called "roads", and the Track Fitter (TF), refining the track quality with high precision fits. The FTK design [1] that works well at the Large Hadron Collider (LHC) Phase I luminosity requires the best of the available technology for tracking in high occupancy conditions. While the new processor is designed for the most demanding LHC conditions, we want to use already existing prototypes, part of them developed for the SLIM5 collaboration [2], to exercise the FTK functions in the new Atlas environment. During Laboratory tests, the EDRO board (Event Dispatch and Read-Out) receives on a clustering mezzanine (able to calculate the pixel and SCT cluster centroids) "fake" detector raw data on S-links from ...

We study large-scale outflows in a sample of 96 star-forming galaxies at 1centroids and maximum extent of the absorption lines, increase with increasing stellar mass with 2-3sigma significance, in agreement with previous results. We study fine structure emission from FeII*, finding several lines of evidence in support of t...

We study the distribution of projected offsets between the cluster X-ray centroid and the brightest cluster galaxy (BCG) for 65 X-ray selected clusters from the Local Cluster Substructure Survey (LoCuSS), with a median redshift of z=0.23. We find a clear correlation between X-ray/BCG projected offset and the logarithmic slope of the cluster gas density profile at 0.04r500 (alpha), implying that more dynamically disturbed clusters have weaker cool cores. Furthermore, there is a close correspondence between the activity of the BCG, in terms of detected H_alpha and radio emission, and the X-ray/BCG offset, with the line emitting galaxies all residing in clusters with X-ray/BCG offsets of 0.02r500, indicating that the total mass may be systematically underestimated in clusters with larger X-ray/BCG offsets. Our results imply a link between cool core strength and cluster dynamical state consistent with the view that cluster mergers can significantly pertu rb cool cores, and set new constraints on models of the ev...

In several migratory cells, the microtubule-organizing center (MTOC) is repositioned between the leading edge and nucleus, creating a polarized morphology. Although our understanding of polarization has progressed as a result of various scratch-wound and cell migration studies, variations in culture conditions required for such assays have prevented a unified understanding of the intricacies of MTOC and nucleus positioning that result in cell polarization. Here, we employ a new SMRT (for sparse, monolayer, round, triangular) analysis that uses a universal coordinate system based on cell centroid to examine the pathways regulating MTOC and nuclear positions in cells plated in a variety of conditions. We find that MTOC and nucleus positioning are crucially and independently affected by cell shape and confluence; MTOC off-centering correlates with the polarization of single cells; acto-myosin contractility and microtubule dynamics are required for single-cell polarization; and end binding protein 1 and light intermediate chain 1, but not Par3 and light intermediate chain 2, are required for single-cell polarization and directional cell motility. Using various cellular geometries and conditions, we implement a systematic and reproducible approach to identify regulators of MTOC and nucleus positioning that depend on extracellular guidance cues. PMID:22193958

A regionalization procedure is proposed to define affinity regions in Andalusia (Southern Spain) regarding maximum and minimum temperature, and precipitation in order to validate a regional climate model (WRF). In situ observations are not suitable for model validation unless they are somehow upscaled. Therefore, a regionalization methodology was adopted to overcome the representation error that arises from the spatial scale disagreement between site-specific observations and model outputs. An observational daily dataset that comprises 412 rain gauges and 120 maximum and minimum temperature series all over Andalusia was used. The observations covered a 10-year period ranging from 1990 to 1999 with no more than 10% of missing values. The original dataset composed by 716 series for precipitation and 243 for temperature were employed to fill the gaps using a correlation method. Precipitation and temperature have been processed separately using the multi-step regionalization methodology formed by three main stages. Firstly, a S-Mode Principal Component Analysis (PCA) was applied to the correlation matrix obtained from daily values to retain principal modes of variability and discard possible information redundancy. Secondly, rotated normalized loadings were used to classify the stations via an agglomerative Clustering Analysis (CA) method to set the number of regions and the centroids associated to those regions. Finally, using the centroids calculated in the previous step and once the appropriate number of regions was identified, a non-hierarchical k-means algorithm was applied to obtain the definitive climate division of Andalusia. The combination of methods attempts to take advantage of their benefits and eliminate their shortcomings when used individually. This multi-step methodology achieves a noticeable reduction of subjectivity in the regionalization process. Furthermore, it is a methodology only based on the data analyzed to perform the regionalization with no a priori assumptions that could influence the classification of the stations. Several configurations were acceptable, but the simplest one was chosen so that the regionalization obtained was not fragmented in excess. Five regions were identified for precipitation and six for temperature, leading to a coherent distribution of the division according to the local features of climate and the topography of the region. Since the main purpose of the regionalization technique is to set both observations and WRF outputs to a comparable spatial scale, some results of this comparison are also presented in order to highlight the main differences among the regions. Acknowledgements: The Spanish Ministry of Science and Innovation, with additional support from the European Community Funds (FEDER), project CGL2007-61151/CLI, and the Regional Government of Andalusia project P06-RNM-01622, have financed this study.

Using the Newtonian method, the equations of motion are developed for the coupled bending-torsion steady-state response of beams rotating at constant angular velocity in a fixed plane. The resulting equations are valid to first order strain-displacement relationships for a long beam with all other nonlinear terms retained. In addition, the equations are valid for beams with the mass centroidal axis offset (eccentric) from the elastic axis, nonuniform mass and section properties, and variable twist. The solution of these coupled, nonlinear, nonhomogeneous, differential equations is obtained by modifying a Hunter linear second-order transfer-matrix solution procedure to solve the nonlinear differential equations and programming the solution for a desk-top personal computer. The modified transfer-matrix method was verified by comparing the solution for a rotating beam with a geometric, nonlinear, finite-element computer code solution; and for a simple rotating beam problem, the modified method demonstrated a significant advantage over the finite-element solution in accuracy, ease of solution, and actual computer processing time required to effect a solution.

The first part of this paper presents a new method for the classification and screening of diatoms in images taken from water samples. The technique can be split into three main stages: segmentation, object feature extraction and classification. The segmentation part consists of two modified thresholding and contour tracing techniques in order to detect the majority of objects present at the sample. From the segmented objects, several features have been extracted and analyzed. For the classification, a diatom training set was considered and the centroids, means and variances of four different classes were found. For the identification process diatoms were classified according with their Mahalanobis distance. The results show the method ability to select at least 80% of usable diatoms from images contaminated with debris. Secondly, full automation of the diatom classification is achieved when multi-focal microscopy is utilized for water sample acquisition. In this case, a necessary preprocessing step is image fusion. A novel wavelet-based fusion method proposed here returns a sharp image that can be directly used for segmentation. For a better understanding of the diatom shape, a 2.5D reconstruction is given.

We present a practical approach to generate stochastic anisotropic samples with Poisson-disk characteristic over a two-dimensional domain. In contrast to isotropic samples, we understand anisotropic samples as non-overlapping ellipses whose size and density match a given anisotropic metric. Anisotropic noise samples are useful for many visualization and graphics applications. The spot samples can be used as input for texture generation, e.g., line integral convolution (LIC), but can also be used directly for visualization. The definition of the spot samples using a metric tensor makes them especially suitable for the visualization of tensor fields that can be translated into a metric. Our work combines ideas from sampling theory and mesh generation. To generate these samples with the desired properties we construct a first set of non-overlapping ellipses whose distribution closely matches the underlying metric. This set of samples is used as input for a generalized anisotropic Lloyd relaxation to distribute noise samples more evenly. Instead of computing the Voronoi tessellation explicitly, we introduce a discrete approach which combines the Voronoi cell and centroid computation in one step. Our method supports automatic packing of the elliptical samples, resulting in textures similar to those generated by anisotropic reaction-diffusion methods. We use Fourier analysis tools for quality measurement of uniformly distributed samples. The resulting samples have nice sampling properties, for example, they satisfy a blue noise property where low frequencies in the power spectrum are reduced to a minimum. PMID:18192714

Optical microscopes are widely used in biological and medical researches. By using the microscope, we can observe cellular movements including intracellular ions and molecules tagged with fluorescent dyes at a high magnification. However, a freely motile cell easily escapes from a 3D field of view of the typical microscope. Therefore, we propose a novel auto-focusing algorithm and develop a auto-focusing and tracking microscope. XYZ positions of a microscopic stage are feedback controlled to focus and track the cell automatically. A bright-field image is used to estimate a cellular position. XY centroids are used to estimate XY positions of the tracked cell. To estimate Z position, we use a diffraction pattern around the cell membrane. This estimation method is so-called Depth from Diffraction (DFDi). However, this method is not robust for individual differences between cells because the diffraction pattern depends on each cellular shape. Therefore, in this study, we propose a real-time correction of DFDi by using 2D Laplacian of an intracellular area as a goodness of the focus. To evaluate the performance of our developed algorithm and microscope, we auto-focus and track a freely moving paramecium. In this experimental result, the paramecium is auto-focused and kept inside the scope of the microscope during 45s. The evaluated focal error is within 5µm, while a length and a thickness of the paramecium are about 200µm and 50µm, respectively.   

Abstract in spanish Estudiamos la microevolución de las poblaciones arcaicas de la costa norte y sus contribuciones morfológicas al Período Formativo. La muestra comprendió 181 individuos pertenecientes a dos colecciones arcaicas de la costa (Morro-Uhle y Morro 1-1/6) y una al formativo (Alto Ramírez) exhumada en el Valle de Azapa. Un total de 29 variables métricas del cráneo fueron analizadas. La variabilidad biológica fue determinada utilizando análisis discriminante y distancias (more) de Mahalanobis (MDS). La estructura de población se analizó utilizando un método basado en teoría genética cuantitativa que predice una relación lineal entre la varianza promedio intragrupal y su distancia hacia el centroide poblacional. Las cuatro muestras analizadas demostraron ser morfológicamente diferentes. La mayor diferencia fue observada entre Plm-7 (Formativo costero) y Alto Ramírez (Formativo valluno), la menor entre Morro-Uhle y Morro 1-1/6, teniendo las otras distancias valores intermedios. El grupo más divergente fue Alto Ramírez y el menos divergente Morro 1-1/6. Un cambio gradual morfológico se observó entre el arcaico (Morro Uhle y Morro 1-1/6) y el Formativo costero (Plm-7) indicando una contribución morfológica (genética) de los pescadores arcaicos a las poblaciones formativas en la costa del norte de Chile, sin excluir, por cierto, flujo génico de otros grupos de la región centro-sur andina Abstract in english The microevolution of the archaic populations from Chile's northern coast and its morphological contribution to Formative period groups was studied. The sample comprised 181 individuals belonging to two Archaic (Morro-Uhle and Morro 1-1/6) and one Formative (Playa Miller-7 [Plm-7]) series of the coast and one sample from the Formative (Alto Ramírez) exhumed at the Azapa Valley. A total of 29 metric variables of the cranium were analyzed. Biological variability was assess (more) ed using discriminant analysis and Mahalanobis' D² distance stadistic (MDS). Population structure was inferred using a method based on quantitative genetic theory that predicts a lineal relationship between average within-group phenotypic variance and group distance to the population centroid. The four samples studied proved to be different from a morphologic point of view. The greatest distance was observed between Plm-7 (coast Formative) and Alto Ramirez (valley Formative), the least between Morro-Uhle and Morro 1-1/6, the remaining distances presenting intermediate values. Regarding the total population, the most divergent group was Alto Ramírez and the least divergent was Morro1-1/6. A gradual biologic change was observed between Archaic (Morro Uhle and Morro 1-1/6) and coastal Formative populations (Plm-7) pointing to a morphological (genetic) contribution of Archaic fishermen to Formative population of Chile's northern coast, without excluding gene flow from other groups of the South Central Andean Area

Merging clusters of galaxies are unique in their power to directly probe and place limits on the self-interaction cross-section of dark matter. Detailed observations of several merging clusters have shown the intracluster gas to be displaced from the centroids of dark matter and galaxy density by ram pressure, while the latter components are spatially coincident, consistent with collisionless dark matter. This has been used to place upper limits on the dark matter particle self-interaction cross-section of order 1 cm2 g–1. The cluster A520 has been seen as a possible exception. We revisit A520 presenting new Hubble Space Telescope Advanced Camera for Surveys mosaic images and a Magellan image set. We perform a detailed weak-lensing analysis and show that the weak-lensing mass measurements and morphologies of the core galaxy-filled structures are mostly in good agreement with previous works. There is, however, one significant difference: We do not detect the previously claimed "dark core" that contains excess mass with no significant galaxy overdensity at the location of the X-ray plasma. This peak has been suggested to be indicative of a large self-interaction cross-section for dark matter (at least ~5? larger than the upper limit of 0.7 cm2 g–1 determined by observations of the Bullet Cluster). We find no such indication and instead find that the mass distribution of A520, after subtraction of the X-ray plasma mass, is in good agreement with the luminosity distribution of the cluster galaxies. We conclude that A520 shows no evidence to contradict the collisionless dark matter scenario. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 12253. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

A two-layer air pollution model is developed for the case when inter-layer mixing is continuous, but slower than intra-layer vertical mixing. The model was designed to examine the implications of inter-layer tranport for ground-level impacts. The model equations, consisting of two coupled partial differential equations, are solved numerically by the method of characteristics. In the case of first order chemical reactions, the zero and first order moments are computed in order to determine the locations of the centroids of pollutant mass. The model indicated that a pulse of pollutants emitted at ground level can result in bifurcation of a pollutant plume due to the wind directional shear between the two atmospheric layers. The residual concentrations due to the transport between layers can move upwind, downwind or remain stationary with respect to the ground level winds, depending on the speed and orientation of the winds aloft. Several specific cases are described, and, in each case, the behavior of the residual plume would not be expected from the surface layer winds that are normally used to predict the transport and dispersion of pollutants. In addition, it appears that the characteristic exchange rate between the air aloft and the surface mixing layer is large enough that the winds aloft must be considered when describing long range transport or the multi-day impacts of a pollutant.

Crystal structure of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl ester has been solved by X-ray diffraction. The crystals are triclinic, space group P1¯, with a=5.4435(18) Å, b=12.248(2) Å, c=13.6769(15) Å, ?=70.274(12)°, ?=81.630(15)°, ?=77.60(2)°, Z=2 and R=0.0519. The molecules are strongly linked in dimers by hydrogen bonds, forming rings with R22(10) as the graph descriptor. The pyrrolic ring, slightly distorted from the C2v symmetry, is almost planar. This plane makes an angle of 75.5(1)° with the L.S. plane containing the methoxy-carbonyl group and an angle of 13.6(1)° with the L.S. plane containing the benzyl group. The internal cohesion of the crystal is supported by three C H…? intermolecular interactions, with H…Cg (ring centroid) distances ranging from 3.060 to 3.377 Å. Several calculations were performed for the dimer such as density functional theory with a hybrid functional B3LYP, semi-empirical self-consistent field (AM1 and PM3) and self-consistent field molecular orbital Hartree Fock (SCF-MO HF) method. The latter calculation was repeated for the isolated molecule. In all cases the minimum of the energy is achieved with the substituents assuming a more perpendicular position to the central aromatic ring than is experimentally observed.

We assessed the potential of white-tailed deer (WTD) (Odocoileus virginianus) to be a sentinel for human cases of Lyme disease (LD) in Indiana using location data from a 3-year survey of approximately 3400 hunted deer with associated tick Ixodes scapularis and Borrelia burgdorferi (Bb) data. Data on human LD cases at the county level were obtained from the Indiana Department of Health. All data were assigned to county centroids to match the resolution of the LD data before creating optimized trend surfaces for LD incidence, hunted deer count, Ixodes scapularis and Bb prevalence. To determine whether LD was spatially associated with the areas of high densities of deer, deer with Ixodes scapularis and deer with ticks infected with Bb, we used spatial analysis with distance indices (SADIE). The SADIE analysis found significant spatial association between LD and the distribution of three organismal predictor variables, that is, WTD, Ixodes ticks and Bb. Lyme disease incident rate varied between 0.08 cases per 10?000 habitants (Johnson county) and 5.9 cases per 10?000 habitants (Warren county). In conclusion, WTD can be used as an accurate and cost-effective sentinel for human LD. This method will permit public health workers to identify potentially endemic areas independently of human case reports. PMID:22776734

A method is developed for sensitivity analysis and optimization of nodal point locations in connection with vibration reduction. A straightforward derivation of the expression for the derivative of nodal locations is given, and the role of the derivative in assessing design trends is demonstrated. An optimization process is developed in which added lumped masses on the structure are used as design variables to move the node to a preselected location-for example to where a low response amplitude is required or to a point which makes the mode shape nearly orthogonal to the force distribution, thereby minimizing the generalized force. The optimization formulation leads to values for added masses that adjust a nodal location while minimizing the total amount of added mass required to do so. As an example, the node of the second mode of a cantilever box beam model of a rotor blade is relocated to coincide with the centroid of a prescribed force distribution, thereby reducing the generalized force substantially without adding excessive mass. A comparison with an optimization formulation that directly minimizes the generalized force indicates that nodal placement gives essentially a minimum generalized force when the node is appropriately placed.

The Thermal Diffusion Coefficient (TDC) is an input parameter to subchannel code, and it is required to predict local flow conditions in a PWR fuel bundle. TDC influences on the prediction of thermal interchange or mixing of thermal energy between the hot subchannel and interconnected adjacent subchannels. The thermal mixing term in the energy equation is generally represented in terms of a non-dimensional inverse Peclet number or TDC. The parameters associated with thermal mixing can be defined as Eq.(1): TDC =Pe x De/a (1) where: Pe : Inverse Peclet Number (dimensionless) = {epsilon}/ Va De : Equivalent hydraulic diameter, in. a : Lateral flow area between channels per unit length, in{sup 2}/in {epsilon} : Mixing coefficient, in{sup 2}/sec V : Velocity, in/sec TDC is an important factor to evaluate thermal performance. So, flow temperature maps were obtained from the 5x5 rod bundle test section to assess the thermal performance of corresponding fuels. The flow temperatures were measured by thermocouple at the end of heated length and the centroid of subchannel. There are two typical methods to arrange the hot and cold fuel rods as shown in Fig. 1. Configuration Fig. 1(b) is adopted in this work. This paper presents how to determine the TDC and verifies whether all TDC with the effect of mixing vane shape is valid with respect to current design value

We use spectral-element and adjoint methods to iteratively improve crustal and upper mantle images of Europe and the Mid-Atlantic Ridge. 159 earthquakes with magnitudes from 5 to 6.5 recorded at 338 stations are used in the iterative preconditioned conjugate-gradient inversion. Crustal model EPcrust1.0 combined with mantle model S362ANI comprise the initial 3D model EU00. Before the iterative structure inversion, earthquake source parameters (i.e, Centroid moment tensor and location), are recalculated based on 3D Green's functions and Fréchet derivatives. Since we concentrate on upper mantle structures which involve significant anisotropy in the Asthenosphere, transversely isotropic (frequency-dependent) traveltime sensitivity kernels are employed in the structure inversion. Long-period surface waves and short-period body waves are combined to constrain shallow and deep structures simultaneously. With each subsequent iteration, higher frequency signals are added to the inversion. Statistical assessments of traveltime anomalies and point-spread functions enable us to assess the inverted source and structure models. Current model EU25 reveals many interesting features. For instance, slabs underneath the Hellenic, Vrancea and Calabria arcs, slab detachment underneath the Central Apennines, mantle upwelling associated with the Eifel hotspot, slow wavespeed structures in several back-arc basins, e.g., the Ponnonian basin and Tyrrhenian sea, the sharp transition of the Teisseyre-Tornquist suture zone between central Europe and the East European platform.

The microstructure formed by intercellular lipids in the stratum corneum is important for the barrier function of the skin. However, the correlation between lipid composition and microstructure has not yet been clarified. To elucidate the microstructure of intercellular lipids in the stratum corneum, an intercellular lipid model was prepared from ceramide 5 (CER5), cholesterol (CHOL), and palmitic acid (PA), considering the nonuniformity of the lipid components of the stratum corneum. A response surface method incorporating thin-plate spline interpolation (RSM-S) was employed to prepare the CER5/CHOL/PA lipid bilayers. Fluorescence anisotropy of the CER5/CHOL/PA bilayers showed four distinct clusters based on Kohonen's self-organizing maps (SOM). At the centroid formulation of those clusters, the microstructures of CER5/CHOL/PA bilayers were determined using synchrotron X-ray scattering. Three kinds of lamellar structures and two kinds of lateral packing—namely, hexagonal and orthorhombic—were formed. The microstructure of the CER5/CHOL/PA bilayers was likely to be intrinsic to the intercellular lipids in the stratum corneum. In conclusion, the CER5/CHOL/PA bilayers prepared based on RSM-S and SOM were useful as models of the intercellular lipids in the stratum corneum.   

Environmental pollution is a worldwide problem, and metals are the largest group of contaminants in soil. Microarray toxicogenomic studies with ecologically relevant organisms, such as springtails, supplement traditional ecotoxicological research but are presently rather descriptive. Classifier analysis, a more analytical application of the microarray technique, is able to predict biological classes of unknown samples. We used the uncorrelated shrunken centroid method to classify gene expression profiles of the springtail Folsomia candida exposed to soil spiked with six different metals (barium, cadmium, cobalt, chromium, lead, and zinc). We identified a gene set (classifier) of 188 genes that can discriminate between six different metals present in soil, which allowed us to predict the correct classes for samples of an independent test set with an accuracy of 83% (error rate = 0.17). This study shows further that in order to apply classifier analysis to actual contaminated field soil samples, more insight and information is needed on the transcriptional responses of soil organisms to different soil types (properties) and mixtures of contaminants. PMID:20133373

We investigate the distortions due to this shear in the microlensing light curves and in the astrometric microlensing centroid shift trajectories. As expected, the light curve deviation increases as the shear increases and the impact parameter decreases. Although the light curve in the presence of a small shear is similar to the simple Paczynski curve with a slightly smaller impact parameter, the detailed difference between the light curve with and without shear reflects the direction and the magnitude of the shear. The centroid shift trajectory also deviates from a simple ellipse in the presence of shear. The distortion of the centroid shift trajectory increases as the impact parameter decreases, and the shape of the trajectory becomes complicated when the impact parameter becomes small enough. The magnitude of the maximum distortion depends on the magnitude and the direction of the shear. For a source trajectory in a given direction, the time of the maximum distortion depends mostly on the impact parameter ...

The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2011. When these centroid positions are plotted and analyzed as functions of time from each sunspot cycle maximum, there appear to be systematic differences in the positions and equatorward drift rates as a function of sunspot cycle amplitude. If, instead, these centroid positions are plotted and analyzed as functions of time from each sunspot cycle minimum, then most of the differences in the positions and equatorward drift rates disappear. The differences that remain disappear entirely if curve fitting is used to determine the starting times (which vary by as much as eight months from the times of minima). The s...

Results of classical Monte Carlo calculations are presented for the radiation produced by ultra-relativistic positrons incident in a direction parallel to the (110) plane of Si in the energy range 30 to 100 MeV. The results all show the characteristic CR(channeling radiation) peak in the energy range 20 keV to 100 keV. Plots of the centroid energies, widths, and total yields of the CR peaks as a function of energy show the power law dependences of ..gamma../sup 1/ /sup 5/, ..gamma../sup 1/ /sup 7/, and ..gamma../sup 2/ /sup 5/ respectively. Except for the centroid energies and power-law dependence is only approximate. Agreement with experimental data is good for the centroid energies and only rough for the widths. Adequate experimental data for verifying the yield dependence on ..gamma.. does not yet exist.

Determining the precise location of irradiance centroids is a key step for optical triangulation and wavefront sensing based on wavefront slope measurements (as e.g. in Hartmann-Shack aberrometry). Since most aberrometers include some kind of optical relay system to reimage the irradiance distributions provided by the wavefront sampling element onto the irradiance detector, it is esential to ensure that the centroid position and momentum information is preserved along this operation. In optical systems with ABCD difrraction kernels the centroids propagate according to an effective geometrical optics rule. However, the presence of finite apertures partially blocking the incoming beam or non-uniform transmittances unevenly altering its original irradiance distribution may give rise to potentially significant departures from this simple geometrical picture. The potential magnitude of this bias makes it advisable to take proper steps to counteract it in the design of aberrometric setups.

The crystal structure of the title compound, C(16)H(11)F(3)N(4)O(2)S, is stabilized in the form of polymeric chains by N-H?O inter-actions. In the mol-ecular structure, two S(5) ring motifs are formed by intra-molecular N-H?N and N-H?O hydrogen bonding and two S(6) rings are present due to N-H?O and C-H?S inter-actions. ?-? inter-actions are present with distances of 3.2735?(17), 3.563?(2) and 3.664?(4)/3.688?(3)?Å between the centroids of the heterocyclic rings, between the centroids of the heterocyclic ring and trifluoro-meth-oxy-substituted phenyl ring, and between the centroids of the trifluoro-meth-oxy-substituted phenyl rings, respectively. The trifluoro-meth-oxy-phenyl group is disordered over two sites with an occupancy ratio of 0.642?(10):0.358?(10). PMID:21588768

The asymmetric unit of the title compound, C21H18O3, contains two crystallographically independent mol­ecules. The two mol­ecules are linked into cyclic centrosymmetric dimers R 2 2(8) by O—H?O hydrogen bonds. The dihedral angles between the naphthalene ring system and the benzene ring are 87.0?(8) and 84.4?(2)° in the two mol­ecules. The crystal packing is stabilized by O—H?O, C—H?? and ?–? inter­actions [centroid–centroid distance = 3.664?(11)?Å]. In one mol­ecule, the mesityl ring is disordered over two positions [occupancy ratio 0.690?(3):0.690?(3)].

During the formation of the title compound, C(5)H(7)N(2) (+)·C(6)H(2)N(3)O(7) (-), a phenolic proton is transferred to the pyridine N atom. In the crystal structure, the ions are linked by inter-molecular N-H?O and N-H?(O,O) hydrogen bonds into layers running parallel to (100). These layers are connected by weak ?-? stacking inter-actions between symmetry-related pyridine and picric benzene rings with a centroid-centroid distance of 3.758?(2)?Å, forming a three-dimensional network. PMID:21587648

An self-aligning biaxial loading apparatus for use in testing the strength of specimens while maintaining a constant specimen centroid during the loading operation. The self-aligning biaxial loading apparatus consists of a load frame and two load assemblies for imparting two independent perpendicular forces upon a test specimen. The constant test specimen centroid is maintained by providing elements for linear motion of the load frame relative to a fixed crosshead, and by alignment and linear motion elements of one load assembly relative to the load frame.

Near-infrared maps and multicolor photometry of the interacting galaxies IC 694 and NGC 3690 which form Arp 299 (= Markarian 171) are presented. These data reveal for the first time the distribution of nuclei and old red stars in a cataclysmically interacting system. The nuclei are considerably offset from the visual centroids of the galaxies but not from the mass centroids. The near-infrared colors of the most active regions are strongly affected by extinction, emission form hot dust, and bremsstrahlung. Near-infrared emission is also identified with secondary regions of star formation, probably resulting from the galaxies interaction. 24 references.

In the title compound, C22H21N3O4, the central pyrrolidine ring adopts an envelope conformation with the N atom in the flap position. The indoline ring systems are almost perpendic­ular to the mean plane of the pyrrolidine ring, making dihedral angles of 86.4?(8) and 83.1?(8)°. The acetate group attached to the pyrrolidine ring assumes an extended conformation. In thecrystal, N—H?O hydrogen bonds result in the formation of a C(7) chain running along [100]. The crystal packing also features ?–? inter­actions [centroid–centroid distance = 3.2032?(11)?Å].

In the asymmetric unit of the title compound, C(14)H(11)N(5)O(6), there are three crystallographically independent mol-ecules with similar conformations but some differences in bond angles. The mol-ecules are slightly twisted with the dihedral angles between the benzene rings being 10.02?(14), 8.41?(15) and 1.40?(14)°. In each mol-ecule, an intra-molecular N-H?O hydrogen bond generates an S(6) ring motif. In the crystal, mol-ecules are linked by weak C-H?O inter-actions into a three-dimensional network. ?-? inter-actions with centroid-centroid distances of 3.5635?(17)-3.8273?(18)?Å are observed. PMID:22969577

In the title coordination polymer, [HgCl2(C11H9N3)]n, the HgII ion is coordinated by three N atoms from two N-[(E)-pyridin-2-yl­methyl­idene]pyridin-3-amine (L) ligands and two chloride anions in a distorted trigonal–bipyramidal geometry. The two pyridine rings in L form a dihedral angle of 50.0?(2)°. L ligands bridge adjacent HgCl2 units into polymeric chains propagating in [010]. The crystal packing is further stabilized by weak inter­molecular C—H?Cl hydrogen bonds and ?–? inter­actions between the pyridine rings, with a centroid–centroid separation of 3.529?(9)?Å. PMID:12829268

In the title compound, C(15)H(8)Cl(4)N(2)O, the quinoxaline ring system is almost planar, with a dihedral angle between the benzene and pyrazine rings of 3.1?(2)°. The 2,4-dichloro-phenyl ring is approximately perpendicular to the pyrazine ring, with a dihedral angle of 86.47?(13)° between them. The crystal packing features inter-molecular N-H?O hydrogen bonds and ?-? stacking inter-actions, with centroid-centroid distances in the range 3.699?(3)-4.054?(3)?Å. PMID:22904923

In the title compound, C22H13ClN2, the quinoxaline ring system is close to planar [maximum deviation = 0.061?(2)?Å]. The phenyl ring at the 2-position and the phenyl ring of the phenyl­ethynyl substituent make dihedral angles of 49.32?(7) and 11.99?(7) °, respectively, with the quinoxaline mean plane. The two phenyl rings are inclined to one another by 61.27?(9)°. In the crystal, mol­ecules are linked by C—H?? and ?–? inter­actions [centroid–centroid distances = 3.6210?(12) and 3.8091?(12)?Å]. PMID:15761078

Two virtually superimposable mol­ecules comprise the asymmetric unit of the title compound, C27H27N3. The range of dihedral angles between the central 1,3,5-triazine ring and the attached benzene rings is 20.88?(14)–31.36?(14)°, and the shape of each mol­ecule is of a flattened bowl. The crystal packing features weak C—H?? bonds and ?–? inter­actions between triazine and benzene rings [centroid–centroid separations = 3.7696?(17) and 3.7800?(18)?Å] that result in the formation of supra­molecular layers in the ac plane. The crystal studied was a non-merohedral twin with a minor twin component of 20.7?(3)%.

The title compound, C16H11ClO2, is a synthetic flavonoid. The fused-ring system is almost planar, with a mean deviation from the least-squares plane of 0.0204 (2) A. The dihedral angle between the chromene group and the chlorophenyl ring is 50.9 (6)degree, due to unfavourable steric interactions with the Cl atom. Aromatic p-p stacking interactions between the fused benzene (p-rich) and pyran (p-deficient) rings are observed, with a centroid-centroid distance of 3.578 A.

The crystal structure of the title compound, [Co(CO(3))(C(12)H(8)N(2))(2)]NO(3)·H(2)O, consists of Co(III) complex cations, nitrate anions and uncoordinated water mol-ecules. The Co(III) cation is chelated by a carbonate anion and two phenanthroline ligands in a distorted octa-hedral coordination geometry. A three-dimensional supra-molecular structure is formed by O-H?O and C-H?O hydrogen bonding, C-H?? and aromatic ?-? stacking [centroid-centroid distance = 3.995?(1)Å] inter-actions. PMID:21579944

In the title compound, C(9)H(8)N(2)O(2)S, the sulfamoyl NH(2) group is involved in intra-molecular N-H?N and inter-molecular N-H?O hydrogen bonding. In the crystal, molecules are linked via pairs of N-H?O hydrogen bonds, forming inversion dimers, which are further associated through ?-? stacking inter-actions between the quinoline benzene rings [centroid-centroid distance = 3.649?(1)?Å] into a one-dimensional polymeric structure extending along the a axis. PMID:23125632

In the mol-ecule of the title compound, C(14)H(10)ClNO(2)S, the dihedral angle between the almost planar benzothia-zole ring system [maximum deviation = 0.005?(2)?Å] and the benzene ring is 1.23?(9)°. The conformation of the mol-ecule is stabilized by an intra-molecular O-H?N hydrogen bond, forming an S(6) ring motif. In the crystal, mol-ecules are linked into layers parallel to the ac plane by C-H?O hydrogen bonds and ?-? stacking inter-actions [centroid-centroid distance = 3.7365?(12)?Å]. PMID:23125675

In the title compound, C22H23NO4S2, the dihedral angles between the dimethyl­phenyl ring and the two methyl­phenyl rings are 41.19?(15) and 20.50?(17)°; the dihedral angle between the methyl­phenyl rings is 48.11?(14)°. The C—N—S—C torsion angles are ?87.6?(2) and 77.43?(18)°. The only possible directional inter­actions in the crystal are very weak C—H?? inter­actions and very weak ?–? stacking between parallel methyl­phenyl rings [centroid-to-centroid separation = 4.010?(2)?Å and slippage = 1.987?Å].

In the title compound, C(16)H(12)FIO(2)S, the 3-fluoro-phenyl ring makes a dihedral angle of 76.47?(6)° with the mean plane [r.m.s. deviation = 0.013?(2)?Å] of the benzofuran fragment. In the crystal, mol-ecules are linked by weak C-H?O hydrogen bonds,forming chains along the b-axis direction, and an I?O contact [3.204?(2)?Å]. The crystal structure also exhibits slipped ?-? inter-actions between the 3-fluoro-phenyl rings of neighbouring mol-ecules [centroid-centroid distance = 3.683?(3)?Å and slippage = 1.708?(3)?Å]. PMID:23125690

The cross-strip imaging readout employs charge division, and centroiding, of microchannel plate charge signals detected on two orthogonal layers of sense strips to encode event X-Y positions and times. We have developed cross-strip detectors and fully parallel channel position encoding electronics. The front-end amplifiers utilize two 32-channel pre-amplifier ASICs that send signals to a full 64-channel 60MHz ADC circuit followed by a FPGA event-processing board. Tests with a software Finite Impulse Response filter and centroiding algorithm demonstrate 1MHz in combination with firmware-based FPG...

In the title compound, C18H22BrN3OS, the piperidine ring adopts a chair conformation. The mean plane of the thia­zole ring forms dihedral angles of 23.97?(10) and 75.82?(10)° with the mean planes of its adjacent benzene and piperidine rings, respectively. An intra­molecular N—H?N hydrogen bond generates an S(7) ring motif in the mol­ecule. In the crystal, no significant inter­moelcular hydrogen bonds are observed, but a weak ?–? inter­action with a centroid–centroid distance of 3.8855?(13)?Å occurs. PMID:19815577

Speaker change detection involves the identification of the time indices of an audio stream, where the identity of the speaker changes. This paper proposes novel measures for speaker change detection over the centroid model, which divides the feature space into non-overlapping clusters for effective speaker-change comparison. The centroid model is a computationally-efficient variant of the widely-used mixture-distribution based background models for speaker recognition. Experiments on both synthetic and real-world data were performed; the results show that the proposed approach yields promising results compared with the conventional statistical measures.   

In the mol­ecule of the title compound, C16H14O2, a substituted benzil, the dicarbonyl unit has an s-trans conformation. This conformation is substanti­ated by the O—C—C—O torsion angle of 108.16?(15)°. The dihedral angle between the two aromatic rings is 72.00?(6)°. In the crystal structure, neighbouring mol­ecules are linked together by weak inter­molecular C—H?O hydrogen bonds and weak inter­molecular C—H?? inter­actions. In addition, the crystal structure is further stabilized by inter­molecular ?–? inter­actions with centroid–centroid distances in the range 3.6000?(8)–3.8341?(8)?Å.

In the title compound, C20H14N4, the dihedral angles between the central benzene ring and the pendant benzimidazole ring systems are 46.60?(15) and 47.89?(16)°. The dihedral angle between the benzimidazole ring systems is 85.62?(12)° and the N atoms lie to the same side of the mol­ecule. In the crystal, mol­ecules are linked by C—H?N inter­actions and weak aromatic ?–? stacking [shortest centroid–centroid separation = 3.770?(2)?Å] is observed.

In the title compound, C29H24N4O4S3, the two N-tosyl­benzimidazolyl unit are connected through a —S—CH2— fragment, the dihedral angle between the benzimidazole rings being 76.09?(5)°. The methyl­thio group is disordered with respect to exchange of the S and C atoms in a 0.547?(4):0.453?(4) ratio. In the crystal, C—H?O and C—H?? inter­actions connect adjacent mol­ecules into infinite layers parallel to the ab plane. The crystal packing is further stabilized by a ?–? inter­action [centroid–centroid separation = 3.5187?(4)?Å].

In the title compound, C16H14N2O3·4H2O, the dihedral angle between the mean planes of the benzimidazole ring system and benzene ring is 2.9?(1)°. The aldehyde group is disordered over two sets of sites with refined occupancies of 0.559?(4) and 0.441?(4). In the crystal, extensive inter­molecular O—H?O, O—H?N and N—H?O hydrogen bonds in concert with weak ?–? stacking inter­actions [centroid–centroid distances = 3.6104?(9), 3.6288?(9) and 3.9167?(10)?Å] create a three-dimensional network.

In the title salt, C13H19N2 +·BF4 ?, an ionic liquid, the butyl and ethyl substituents bonded to the N atoms of the imidazole ring [r.m.s. deviation = 0.019?(1)?Å] adopt equatorial positions. The crystal structure exhibits slipped ?–? inter­actions between the imidazole and benzene rings of neighbouring mol­ecules [centroid–centroid distance = 3.529?(2)?Å]. In the tetra­fluoro­borate anion, the B and F atoms are disordered over two sets of sites with site-occupancy factors of 0.813?(7) and 0.187?(7).

In the title molecular salt, C24H24N5 +·C6H2N3O7 ?, the dihedral angle between the benzimidazole rings of the cation is 5.041?(2)°. In the anion, the three nitro groups make dihedral angles of 2.468?(3), 12.795?(3) and 24.958?(4)° with respect to the central ring. In the crystal, weak aromatic ?–? stacking [centroid–centroid distance = 3.599?(15)?Å] consolidates the packing. In addition, an intra­molecular N—H?N hydrogen bond is observed.

We report results from extensive new XMM- Newton observations of the ultraluminous X-ray source (ULX) NGC 5408 X-1, one of the few ULXs to show quasi-periodic X-ray variability. We detect quasi-periodic oscillations (QPOs) in each of four new (approximately equal 100 ks each) pointings, expanding the range of frequencies and rms amplitudes observed from the source to 10-40 mHz and 10-45 %, respectively. However, similarly significant variations in the power-law photon spectral index, Gamma, are not observed. We use the results of timing and energy spectral modeling to compare with the timing and spectral correlations seen in stellar-mass systems. We find that the qualitative nature of the timing and energy spectra of NGC 5408 X-1 are very similar to stellar-mass black holes in the steep power-law state exhibiting Type-C QPOs. However, in order for this analogy to quantitatively hold we must only be seeing the so-called saturated portion of the QPO frequency - photon index (or disk flux) relation. Assuming this to be the case, we place a lower limit on the mass of NGC 5408 X-1 of approx greater than 800 Solar Mass. Alternatively, the QPO centroid frequency is largely independent of the spectral parameters, in which case a close analogy of NGC 5408 X-1's mHz QPOs with Type-C QPOs in stellar systems is problematic. Measurement of the source's timing properties over a greater range of spectral parameters (in particular the spectral index) is needed in order to definitively resolve this ambiguity. We searched all the available data for both a broad Fe emission line as well as high frequency QPO analogs (0.1 - 1 Hz), but detected neither. We place upper limits on the equivalent width of any Fe emission feature in the 6 - 7 keY band, and of the amplitude (rms) of a high frequency QPO analog of approx equal 10 eV and approx equal 4%, respectively.

Sensory experience typically depends on the ensemble activity of hundreds or thousands of neurons, but little is known about how populations of neurons faithfully encode behaviorally important sensory information. We examined how precisely speed of movement is encoded in the population activity of magnocellular-projecting parasol retinal ganglion cells (RGCs) in macaque monkey retina. Multi-electrode recordings were used to measure the activity of approximately 100 parasol RGCs simultaneously in isolated retinas stimulated with moving bars. To examine how faithfully the retina signals motion, stimulus speed was estimated directly from recorded RGC responses using an optimized algorithm that resembles models of motion sensing in the brain. RGC population activity encoded speed with a precision of approximately 1%. The elementary motion signal was conveyed in approximately 10 ms, comparable to the interspike interval. Temporal structure in spike trains provided more precise speed estimates than time-varying firing rates. Correlated activity between RGCs had little effect on speed estimates. The spatial dispersion of RGC receptive fields along the axis of motion influenced speed estimates more strongly than along the orthogonal direction, as predicted by a simple model based on RGC response time variability and optimal pooling. on and off cells encoded speed with similar and statistically independent variability. Simulation of downstream speed estimation using populations of speed-tuned units showed that peak (winner take all) readout provided more precise speed estimates than centroid (vector average) readout. These findings reveal how faithfully the retinal population code conveys information about stimulus speed and the consequences for motion sensing in the brain. PMID:15625091

Abstract in spanish La descripción de patrones morfológicos del perfil nasal en la población que orienten la toma de decisiones y evaluación terapéutica, y que aseguren el éxito de técnicas como la reconstrucción facial forense, ha sido el objetivo de numerosos estudios basados en el uso de morfometría tradicional. El objetivo de este trabajo es el estudio del perfil nasal en una muestra de población chilena utilizando herramientas de la morfometría geométrica. Se utilizaron las (more) radiografías de una muestra mixta de 156 individuos adultos y 14 hitos en perfil duro y blando. Se realizó el análisis de Procusto, seguido de análisis de componentesprincipales para el estudio exploratorio de la forma, regresión de los componentes de la forma contra el tamaño de centroide para el estudio del efecto alométrico en la forma del perfil nasal, análisis discriminante para la variable sexo y prueba de validación cruzada. Los resultados muestran que de las variables controladas, el tamaño y luego el sexo serían las que más explican la variabilidad observada, sin embargo el peso general de estas variables es bajo, sugiriendo la presencia de otras variables no controladas, y un gran componente de variación entre los individuos. Morfológicamente, se observa que los perfiles de mayor tamaño, de mayor frecuencia en hombres, presentan un punto nasal más descendido y un dorso nasal más curvo, así como un labio más expandido verticalmente. Desde el punto de vista estético, se sugiere dar importancia a la evaluación individual con fines terapéuticos. En antropología forense, se sugiere la prudencia en las conclusiones basadas en técnicas de reconstrucción debido a la falta de patrones morfológicos que orienten la técnica de manera certera. Abstract in english The search of morphological patterns of nasal profile using traditional morphometrics has been the goal of several studies aiming to orient therapeutical planning and forensic techniques such as facial reconstruction. The present study aims to find and describe such patterns with geometric morphometric tools in a sample of Chilean population with geometric morphometric tools. We used the lateral X-rays of 156 individuals (men and women) and 14 landmarks in bone and soft t (more) issues. Procrustes analysis was performed followed by principal component analysis to assess general shape variation, regression of shape components against centroid size to study to allometric effect and discriminant analysis by sex with cross-validation test. Our results show the lack of shape patterns, and that the size, followed by sex, explains within a limited scope the shape changes which suggests the presence of uncontrolled variables and a high effect of inter-individual variation. In general terms bigger profiles, more frequent in men, show a lower Pronasal point, a more prominent nasal dorsum with a thicker layer of soft tissue, and a vertically expanded upper lip. We suggest the reassessment of the importance of individual aesthetic evaluation for clinical purposes, and recommend caution in concluding results based on forensic reconstruction techniques.

[1] The median Doppler shift of radar echoes is analyzed in measurements by ENVISAT's Advanced Synthetic Aperture Radar (ASAR) over the ocean. This Doppler centroid differs from a predicted signal based on the predicted motion of the satellite and Earth. This anomaly, converted to a surface Doppler ...

In the title compound, C(16)H(13)FO(4), the aromatic rings enclose an angle of 73.68?(6)°. In the crystal, C-H?O and C-H?F contacts connect the mol-ecules into a three-dimensional network. The shortest inter-centroid distance between two aromatic ?-systems is 3.6679?(7)?Å and is apparent between the fluorinated phenyl groups. PMID:22347113

Field recordings of echolocation signals produced by Heaviside's dolphins (Cephalorhynchus heavisidii) were made off the coast of South Africa using a hydrophone array system. The system consisted of three hydrophones and an A-tag (miniature stereo acoustic data-logger). The mean centroid frequency ...

Feb 1, 2011 ... the target star to detect by adaptive optics (AO), speckle imaging, or centroid motion. ..... analysis, 69% are smaller than Neptune (Rp= 3.8 R!). ..... guide to content of the tables, a simple model was developed to provide a ...

The title compound, C16H13N, is essentially planar [maximum deviation from the least-squares plane = 0.081?(3)?Å], with a dihedral angle of 1.65?(13)° between the planes of the indole and benzene rings. In the crystal, there are no significant inter­molecular ?–? inter­actions [minimum ring centroid...

the data is distributed across the processors and a random choice of the k centroids are also ... clustering are as follows: • Compute weighted adjacency matrix W ? Rd×d where Wij. = ..... [2] N. M. Ball and R. J. Brunner. Data Mining and ...

In the title compound, C9H5N3, the quinoxaline ring is essentially planar, with a maximum deviation of 0.012?(1)?Å. Short inter­molecular distances between the centroids of the 2,3-dihydro­pyrazine and benzene rings [3.6490?(5)?Å] indicate the existence of ??? inter­actions. In the crystal packing, ...

The asymmetric unit of the title compound, 2C16H14N4·C8H6N2, consits of one mol­ecule of N,N?-bis­(pyridin-2-yl)benzene-1,4-diamine (PDAB) and one half-mol­ecule of quinoxaline (QX) that is located around an inversion centre and disordered over two overlapping positions. The PDAB mol­ecule adopts a non-planar conformation with an E configuration at the two partially double exo C N bonds of the 2-pyridyl­amine units. In the crystal, these self-complementary units are N—H?N hydrogen bonded via a cyclic R 2 2(8) motif, creating tapes of PDAB mol­ecules extending along [010]. Inversion-related tapes are arranged into pairs through ?–? stacking inter­actions between the benzene rings [centroid–centroid distance = 3.818?(1)?Å] and the two symmetry-independent pyridine groups [centroid–centroid distance = 3.760?(1)?Å]. The QX mol­ecules are enclosed in a cavity formed between six PDAB tapes.

In the crystal structure of the title substituted ferrocene complex, [Fe(C19H18O2P)2], the FeII atom lies on a twofold rotation axis, giving an eclipsed cyclo­penta­dienyl conformation with a ring centroid separation of 3.292?(7)?Å and an Fe—C bond-length range of 2.0239?(15)–2.0521?(15)?Å. In the l...

A technique is described in which the centroid of induced charge on cathode strips in a proportional chamber can be determined with reduced differential and integral nonlinearity, without increasing the number of readout channels. It is based on capacitive charge division from intermediate cathode strips to adjacent readout strips, and may be applied to a variety of position readout principles.

In the crystal structure of the title compound, C12H18S5, no significant inter­molecular ?–? inter­actions are found. Weak inter­molecular C—S?? [S?centroid = 3.787?(1)?Å] inter­actions and van der Waals forces may be effective in the stabilization of the structure.

science community that these data systems are important, integral components ..... must be a distributed system in any event, because that is the only feasible long-term path to ..... AMPTE/CCE Science Data Center at JHU/APL ..... particular, the level referred to as Level 2 (below) represents the centroid of a broad range of ...

and modeling will play an integral role in the Senti- nels mission .... ble, within to 2 scattering mean free paths (i.e., at ...... Laboratory (APL) and the Jet Propulsion Labora- ...... angular rate and position relative to the solar centroid using the ...

May 17, 1975 ... of the propagation path over the North Pole (i.e., there is little or no possi- ..... centroid and other calibration quantities, but also to measure and store ...... (laser ). APL doppler,. AMS secor raw APL doppler. ANNA 1 doppler .... proposed by Uotila (1960), that sums contributions to the integrals from the whole ...

Jan 31, 1999 ... path. Heat pipes are a viable low mass option using a closed two-phase liquid- flow ..... The JSC APL site is also given in Appendix. K. ...... integral cascade curves, i.e. the mean energy deposited .... Fitting these centroids ...

Other vehicles are serviced, an integral number of times per commutation cycle. ...... As the radar frequency increases, the path attenuation increases and this ...... Stations at the face-centroids of a tetrahedron can be regarded as located at the ...... 1Newton, R. R., Damping of a Gravitationally Stabilized Satellite, APL Report ...

... in ACTVEH and the integration of model dynamics equations (e.g., actuator motion) in the other. 2-2 ..... velocity contribution due to wind speed and direction, flight path angle,. Mach number, dynamic ...... x-accelerometer: ]L ~ ^apl'ap2' ap3' ...... Defines the vector R from the centroid of the probability ellipse to the intercept ...

path runs above the. 74 ° magnetic line for a third of its length, namely from ...... 2( a). The positions marked by a + are the average positions of the centroids of the ...... Six. Ge;ger-Muller detectors cover four integral energy channels for electrons ..... in. 1967-68,. APL. Preprint,. October,. 1970. (Submitted to J. Geophys. Res.) ...