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Author |
Mendez, V.; Amoros, G.; Kaci, M. |
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Title |
A Decentralized Deployment Strategy and Performance Evaluation of LCG File Catalog Service |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of Grid Computing |
Abbreviated Journal |
J. Grid Comput. |
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Volume |
9 |
Issue |
3 |
Pages |
345-354 |
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Keywords |
Distributed computing; Grid computing; Performance; Catalog |
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Abstract |
The LHC Computing Grid (LCG) leads by CERN, has solved with the LCG File Catalog (LFC) the major problem of scaling the data management catalog. However, additional performance issues should be faced to deploy a painless catalog service. With this aim, we present a decentralized LFC server configuration, and its performance evaluation compared with the traditional LFC deployment. A performance analysis is shown, including not only the catalog server, but also analysing the client side overhead. We find that the LFC service has in the clients a relevant workload of the overall service. The experimental results show that the proposed LFC deployment for servers and clients, improves the performance of the service. |
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Address |
[Munoz, VM; Vicente, GA; Kaci, M] CSIC, Mixed Inst, Inst Fis Corpuscular IFIC, Grid & E Sci Grp, Valencia 46071, Spain, Email: vmendez@ific.uv.es |
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Publisher |
Springer |
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English |
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ISSN |
1570-7873 |
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Notes |
WOS:000293973700004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration  |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
721 |
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Author |
Pino, F.; Roe, N.; Orero, A.; Falcon, C.; Rojas, S.; Benlloch, J.M.; Ros, D.; Pavia, J. |
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Title |
Development of a variable-radius pinhole SPECT system with a portable gamma camera |
Type |
Journal Article |
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Year |
2011 |
Publication |
Revista Española de Medicina Nuclear |
Abbreviated Journal |
Rev. Esp. Med. Nucl. |
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Volume |
30 |
Issue |
5 |
Pages |
286-291 |
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Keywords |
SPECT; Small animal; Pinhole; Portable gamma camera; Continuous scintillator |
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Abstract |
Objective: To develop a small-animal SPECT system using a low cost commercial portable gamma camera equipped with a pinhole collimator, a continuous scintillation crystal and a position-sensitive photomultiplier tube. Material and methods: The gamma camera was attached to a variable radius system, which enabled us to optimize sensitivity and resolution by adjusting the radius of rotation to the size of the object. To investigate the capability of the SPECT system for small animal imaging, the dependence of resolution and calibration parameters on radius was assessed and acquisitions of small phantoms and mice were carried out. Results: Resolution values, ranging from 1.0 mm for a radius of 21.4 mm and 1.4 mm for a radius of 37.2 mm were obtained, thereby justifying the interest of a variable radius SPECT system. Conclusions: The image quality of phantoms and animals were satisfactory, thus confirming the usefulness of the system for small animal SPECT imaging. |
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Address |
[Pino, F; Roe, N; Ros, D] Univ Barcelona, Fac Med, Unitat Biofis, Barcelona 7, Spain, Email: fpino@iconcologia.net |
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Elsevier Science Inc |
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English |
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ISSN |
0212-6982 |
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Notes |
WOS:000294659400004 |
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no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
753 |
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Author |
Galli, P.; Ortin, T.; Perz, J.; Shahbazi, C.S. |
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Title |
Non-extremal black holes of N=2, d=4 supergravity |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
041 |
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Abstract |
We propose a generic recipe for deforming extremal black holes into nonextremal black holes and we use it to find and study the static non-extremal black-hole solutions of several N = 2, d = 4 supergravity models (SL(2, R)/U(1), (CP) over bar (n) and STU with four charges). In all the cases considered, the non-extremal family of solutions smoothly interpolates between all the different extremal limits, supersymmetric and not supersymmetric. This fact can be used to explicitly find extremal non-supersymmetric solutions also in the cases in which the attractor mechanism does not completely fix the values of the scalars on the event horizon and they still depend on the boundary conditions at spatial infinity. We compare (supersymmetry) Bogomol'nyi bounds with extremality bounds, we find the first-order flow equations for the non-extremal solutions and the corresponding superpotential, which gives in the different extremal limits different superpotentials for extremal black holes. We also compute the entropies (areas) of the inner (Cauchy) and outer (event) horizons, finding in all cases that their product gives the square of the moduli-independent entropy of the extremal solution with the same electric and magnetic charges. |
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Series Volume |
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Edition |
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ISSN |
1126-6708 |
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Notes |
WOS:000293741400041 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
761 |
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Author |
Panotopoulos, G.; Tuzon, P. |
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Title |
The physics of a new gauge boson in a Stueckelberg extension of the two-Higgs-doublet model |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
039 |
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Abstract |
String theory constructions using D-brane physics offer a framework where ingredients like extra abelian factors in the gauge group, more than one Higgs doublet and a generalized Green-Schwarz mechanism appear at the same time. Motivated by works towards the direction of obtaining the Standard Model in orientifold constructions, we study in the present work a Stueckelberg extension of the two-Higgs-doublet model. The distinctive features of our model are i) a sharp decay width for the heavy gauge boson, and ii) a charged Higgs boson having two main decay channels at tree level with equal branching ratios. |
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ISSN |
1126-6708 |
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Notes |
WOS:000293741400039 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
763 |
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Author |
Bernabeu, J.; Espriu, D.; Puigdomenech, D. |
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Title |
Gravitational waves in the presence of a cosmological constant |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
84 |
Issue |
6 |
Pages |
063523 - 13pp |
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Abstract |
We derive the effects of a nonzero cosmological constant Lambda on gravitational wave propagation in the linearized approximation of general relativity. In this approximation, we consider the situation where the metric can be written as g(mu nu) = eta(mu nu) + h(mu nu)(Lambda) + h(mu nu)(W), h(mu nu)(Lambda,W) << 1, where h(mu nu)(Lambda) is the background perturbation and h(mu nu)(W) is a modification interpretable as a gravitational wave. For Lambda not equal 0, this linearization of Einstein equations is self-consistent only in certain coordinate systems. The cosmological Friedmann-Robertson-Walker coordinates do not belong to this class and the derived linearized solutions have to be reinterpreted in a coordinate system that is homogeneous and isotropic to make contact with observations. Plane waves in the linear theory acquire modifications of order root Lambda, both in the amplitude and the phase, when considered in Friedmann-Robertson-Walker coordinates. In the linearization process for h(mu nu), we have also included terms of order O(Lambda h(mu nu)). For the background perturbation h(mu nu)(Lambda), the difference is very small, but when the term h(mu nu)(W)Lambda is retained the equations of motion can be interpreted as describing massive spin-2 particles. However, the extra degrees of freedom can be approximately gauged away, coupling to matter sources with a strength proportional to the cosmological constant itself. Finally, we discuss the viability of detecting the modifications caused by the cosmological constant on the amplitude and phase of gravitational waves. In some cases, the distortion with respect to gravitational waves propagating in Minkowski space-time is considerable. The effect of Lambda could have a detectable impact on pulsar timing arrays. |
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Address |
[Bernabeu, J] Univ Valencia, Dept Fis Teor IFIC, CSIC, E-46100 Valencia, Spain |
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Publisher |
Amer Physical Soc |
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Language |
English |
Summary Language |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Notes |
WOS:000295223100005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
766 |
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