4,985 research outputs found
Wiener Reconstruction of Large-Scale Structure from Peculiar Velocities
We present an alternative, Bayesian method for large-scale reconstruction
from observed peculiar velocity data. The method stresses a rigorous treatment
of the random errors and it allows extrapolation into poorly sampled regions in
real space or in k-space. A likelihood analysis is used to determine the
fluctuation power spectrum, followed by a Wiener Filter (WF) analysis to obtain
the minimum-variance mean fields of velocity and mass density. Constrained
Realizations (CR) are then used to sample the statistical scatter about the WF
mean field. The WF/CR method is applied as a demonstration to the Mark III data
with 1200 km/s, 900 km/s, and 500 km/s resolutions. The main reconstructed
structures are consistent with those extracted by the POTENT method. A
comparison with the structures in the distribution of IRAS 1.2Jy galaxies
yields a general agreement. The reconstructed velocity field is decomposed into
its divergent and tidal components relative to a cube of +/-8000 km/s centered
on the Local Group. The divergent component is very similar to the velocity
field predicted from the distribution of IRAS galaxies. The tidal component is
dominated by a bulk flow of 194 +/- 32 km/s towards the general direction of
the Shapley concentration, and it also indicates a significant quadrupole.Comment: 28 pages and 8 GIF figures, Latex (aasms4.sty), submitted to ApJ.
Postscript version of the figures can be obtained by anonymous ftp from:
ftp://alf.huji.ac.il/pub/saleem
An Effective Noise Adaptive Median Filter for Removing High Density Impulse Noises in Color Images
Images are normally degraded by some form of impulse noises during the acquisition, transmission and storage in the physical media. Most of the real time applications usually require bright and clear images, hence distorted or degraded images need to be processed to enhance easy identification of image details and further works on the image. In this paper we have analyzed and tested the number of existing median filtering algorithms and their limitations. As a result we have proposed a new effective noise adaptive median filtering algorithm, which removes the impulse noises in the color images while preserving the image details and enhancing the image quality. The proposed method is a spatial domain approach and uses the 3Ă3 overlapping window to filter the signal based on the correct selection of neighborhood values to obtain the effective median per window. The performance of the proposed effective median filter has been evaluated using MATLAB, simulations on a both gray scale and color images that have been subjected to high density of corruption up to 90% with impulse noises. The results expose the effectiveness of our proposed algorithm when compared with the quantitative image metrics such as PSNR, MSE, RMSE, IEF, Time and SSIM of existing standard and adaptive median filtering algorithms
Development of coordinated research efforts
The experience of ICRISAT with the use of Vertisols in semi-arid India indicates that the key to drastically improved productivity of Vertisols is the effective control of surface soil water which then enables rational use of the land for food and feed production. ILCA, therefore, developed and tested on-station and on-farm research in various highland Vertisol areas an animal-drawn implement for broadbed and furrow construction which was to combine technical efficiency of surface drainage construction with economic viability. Substantial increments in grain and biomass outputs due to enhanced surface drainage were recorded along with convincing economic returns to the farm in the application of this technology. In this chapter, history, objectives, rational, strategies, target areas and structure and organisation of the Vertisol project are presented; and the tasks of the advisory and technical committees, division the tasks of the advisory and technical committees, division of responsibilities between participating institutions, terms of reference for the technical committee, project phases and funding, and assistance by ICRISAt and IBSRAM are discussed
Co-evolution of RDF Datasets
Linking Data initiatives have fostered the publication of large number of RDF
datasets in the Linked Open Data (LOD) cloud, as well as the development of
query processing infrastructures to access these data in a federated fashion.
However, different experimental studies have shown that availability of LOD
datasets cannot be always ensured, being RDF data replication required for
envisioning reliable federated query frameworks. Albeit enhancing data
availability, RDF data replication requires synchronization and conflict
resolution when replicas and source datasets are allowed to change data over
time, i.e., co-evolution management needs to be provided to ensure consistency.
In this paper, we tackle the problem of RDF data co-evolution and devise an
approach for conflict resolution during co-evolution of RDF datasets. Our
proposed approach is property-oriented and allows for exploiting semantics
about RDF properties during co-evolution management. The quality of our
approach is empirically evaluated in different scenarios on the DBpedia-live
dataset. Experimental results suggest that proposed proposed techniques have a
positive impact on the quality of data in source datasets and replicas.Comment: 18 pages, 4 figures, Accepted in ICWE, 201
Recommended from our members
The experiences of carers looking after people with Parkinson's disease who exhibit impulsive and compulsive behaviours: an exploratory qualitative study
BACKGROUND: Impulsive and compulsive behaviours (ICBs) are a serious complication in Parkinson disease (PD) strongly associated with dopamine replacement therapy used to treat patients. These behaviours comprise abnormal activities such as pathological gambling, binge eating, compulsive shopping, and hypersexuality. These behaviours place a considerable burden on patients and on their carers and families. The aim of this qualitative study is to understand the experiences of carers who were confronted by the development of these behaviours.
DESIGN: An exploratory qualitative study.
METHODS: Using a convenience sampling approach, 13 carers were recruited to participate in semi-structured interviews. Interviews were conducted over the telephone. Verbatim transcripts were analysed used a thematic analysis approach. COREQ guidelines were adhered to in the reporting of this study.
RESULTS: Five main themes were identified: (1) realisation - developing awareness of ICB symptoms and their causes; (2) reacting - confronting and attempts to manage ICBs; (3) reaching out - help-seeking and selective disclosure; (4) reframing - shifting perspectives on ICBs over time; and (5) resignation - impact on relationships and facing the future.
CONCLUSIONS: The profound impact of ICBs on quality of life, relationships, and economic stability was clear in the carers' accounts. Possible avenues for future clinical research are suggested.
RELEVANCE TO CLINICAL PRACTICE: The potentially devastating effects of ICBs provide a strong imperative for nurses and other health professionals to ensure that close monitoring for symptom development together with patient education are always part of practice
Analysis of the convergence history of fluid flow through nozzles with shocks
Convergence of iterative methods for the solution of the steady quasi-one-dimensional nozzle problem with shocks is considered. The finite-difference algorithms obtained from implicit schemes are used to approximate both the Euler and Navier-Stokes Equations. These algorithms are investigated for stability and convergence characteristics. The numerical methods are broken down into their matrix-vector components and then analyzed by examining a subset of the eigensystem using a method based on the Arnoldi process. The eigenvalues obtained by this method are accurate to within 5 digits for the largest ones and to within 2 digits for the ones smaller in magnitude compared the elgenvalues obtained using the full Jacobian. In the analysis we examine the functional relationship between the numerical parameters and the rate of convergence of the iterative scheme. Acceleration techniques for iterative methods like Wynn\u27s e-algorithm are also applied to these systems of difference equations in order to accelerate their convergence. This acceleration translates into savings in the total number of iterations and thus the total amount of computer time required to obtain a converged solution. The rate of convergence of the accelerated system is found to agree with the prediction based on the eigenvalues of the original iteration matrix. The ultimate goal of this study is to extend this elgenvalue analysis to multi-dimensional problems and to quantitatively estimate the effects of different parameters on the rate of convergence
Neighborhood social processes as moderators between racial discrimination and depressive symptoms for African American adolescents
Racial discrimination is associated with numerous psychological consequences, including increased depressive symptoms for African American adolescents (Brody et al., 2006; Wong, Eccles, & Sameroff, 2003). Adolescentsâ perceptions of their neighborhood can influence how youth interpret and manage racial discrimination (Sampson, Morenoff, & GannonâRowley, 2002). Yet little is known about how adolescent perceptions of neighborhood cohesion and neighborhood disorganization protect or exacerbate the effects of racial discrimination, or how these effects vary by youthâs gender. Therefore, the current study examined whether neighborhood social cohesion and neighborhood disorganization moderated the association between racial discrimination and depressive symptoms for African American adolescents and how the effects differ for boys and girls. Participants were 106 African American adolescents (57% female; mean age 15.14) from an urban metropolitan area. Regression analyses suggest that perceptions of neighborhood social cohesion protected against racial discrimination for boys and girls. Additionally, the results indicate that when boys perceive less neighborhood disorganization, racial discrimination has a greater influence on their depressive symptoms. Findings have implications for intervention and prevention efforts that enhance and utilize positive neighborhood social processes for youth contending with racial discrimination.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145257/1/jcop21970_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145257/2/jcop21970.pd
Bandwidth Enhancement in Microstrip Patch Antenna Using Rhombus Shape Slot
The Microstrip antennas are the low profile radiators. It is so because of their numerous features such as low volume, compactness, low fabrication cost and mechanical robustness. Numerous techniques have been suggested to improve the Microstrip patch antenna characteristics. In this paper we discuss the slot coupled patch antenna, one with a rectangular patch and other one with a rhombus shaped patch. And study the antenna characteristics of both the antenna such as bandwidth, radiation loss and gain. The results indicate the impact of changing patch on the antenna performance. To excite the structure the microstrip line is placed below the slot. The slot is made between the feed line and the radiating patch substrate. Fields from the microstrip line will be coupled to the patch through this narrow slot. ANSYS HFSS is used to carry out the procedure
DOI: 10.17762/ijritcc2321-8169.150313
- âŠ