3,129 research outputs found

    WOODCUT BLOCKS OF THE “SCUOLA DEL LIBRO” OF URBINO: A SCIENTIFIC APPROACH FOR CONSERVATION

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    none4noopenM.L. Amadori, N. Macchioni, G. Adami, C. CaprettiAmadori, M. L.; Nicola, Macchioni; Giampiero, Adami; Chiara, Caprett

    Cluster luminosity function and n^th ranked magnitude as a distance indicator

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    We define here a standard candle to determine the distance of clusters of galaxies and to investigate their peculiar velocities by using the n^{th} rank galaxy (magnitude mn_n). We address the question of the universality of the luminosity function for a sample of 28 rich clusters of galaxies (cz≃20000km/scz \simeq 20000 km/s) in order to model the influence on mnm_n of cluster richness. This luminosity function is found to be universal and the fit of a Schechter profile gives α=−1.50±0.11\alpha = -1.50 \pm 0.11 and Mbj∗=−19.91±0.21M_{bj}* = -19.91 \pm 0.21 in the range [-21,-17]. The uncorrected distance indicator mnm_n is more efficient for the first ranks n. With n=5, we have a dispersion of 0.61 magnitude for the (mn_n,5log(cz)) relation. When we correct for the richness effect and subtract the background galaxies we reduce the uncertainty to 0.21 magnitude with n=15. Simulations show that a large part of this dispersion originates from the intrinsic scatter of the standard candle itself. These provide upper bounds on the amplitude σv\sigma_v of cluster radial peculiar motions. At a confidence level of 90%, the dispersion is 0.13 magnitude and σv\sigma_v is limited to 1200 km/s for our sample of clusters.Comment: 9 pages, 7 postscript figures, LateX A&A, accepted in A&

    Reduction criterion for separability

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    We introduce a separability criterion based on the positive map Γ:ρ→(Tr ρ)-ρ, where ρ is a trace-class Hermitian operator. Any separable state is mapped by the tensor product of Γ and the identity into a non-negative operator, which provides a simple necessary condition for separability. This condition is generally not sufficient because it is vulnerable to the dilution of entanglement. In the special case where one subsystem is a quantum bit, Γ reduces to time reversal, so that this separability condition is equivalent to partial transposition. It is therefore also sufficient for 2×2 and 2×3 systems. Finally, a simple connection between this map for two qubits and complex conjugation in the “magic” basis [Phys. Rev. Lett. 78, 5022 (1997)] is displayed

    Holographic Heat engine within the framework of massive gravity

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    Heat engine models are constructed within the framework of massive gravity in this paper. For the four-dimensional charged black holes in massive gravity, it is shown that the heat engines have a higher efficiency for the cases m2>0m^2>0 than for the case m=0m=0 when c1<0,c2<0c_1<0, c_2<0. Considering a specific example, we show that the maximum efficiency can reach 0.92190.9219 while the efficiency for m=0m=0 reads 0.50140.5014. The existence of graviton mass improves the heat engine efficiency significantly. The situation is more complicated for the five-dimensional neutral black holes. Not only the c1,c2,m2c_1, c_2, m^2 exert influence on the efficiency, but also the constant c3c_3 corresponding to the third massive potential contributes to the efficiency. When c1<0,c2<0,c30c_1<0, c_2<0, c_30 is higher than that of the case m=0m=0. By studying the ratio η/ηC\eta/\eta_C, we also probe how the massive gravity influences the behavior of the heat engine efficiency approaching the Carnot efficiency.Comment: 9pages,4figure

    Redshifts in the Southern Abell Redshift Survey Clusters. I. The Data

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    The Southern Abell Redshift Survey contains 39 clusters of galaxies with redshifts in the range 0.0 < z < 0.31 and a median redshift depth of z = 0.0845. SARS covers the region 0 21h (while avoiding the LMC and SMC) with b > 40. Cluster locations were chosen from the Abell and Abell-Corwin-Olowin catalogs while galaxy positions were selected from the Automatic Plate Measuring Facility galaxy catalog with extinction-corrected magnitudes in the range 15 <= b_j < 19. SARS utilized the Las Campanas 2.5 m duPont telescope, observing either 65 or 128 objects concurrently over a 1.5 sq deg field. New redshifts for 3440 galaxies are reported in the fields of these 39 clusters of galaxies.Comment: 20 pages, 5 figures, accepted for publication in the Astronomical Journal, Table 2 can be downloaded in its entirety from http://trotsky.arc.nasa.gov/~mway/SARS1/sars1-table2.cs

    The use of Minimal Spanning Tree to characterize the 2D cluster galaxy distribution

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    We use the Minimal Spanning Tree to characterize the aggregation level of given sets of points. We test 3 distances based on the histogram of the MST edges to discriminate between the distributions. We calibrate the method by using artificial sets following Poisson, King or NFW distributions. The distance using the mean, the dispersion and the skewness of the histogram of MST edges provides the more efficient results. We apply this distance to a subsample of the ENACS clusters and we show that the bright galaxies are significantly more aggregated than the faint ones. The contamination provided by uniformly distributed field galaxies is neglectible. On the other hand, we show that the presence of clustered groups on the same cluster line of sight masked the variation of the distance with the considered magnitude.Comment: 9 pages, 7 postscript figures, LateX A\{&}A, accepted in A\{&}

    Image Coding with Face Descriptors Embedding

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    4siContent descriptors, useful for browsing and retrieval tasks, are generally extracted and treated as a separate entity with respect to the nature of the content itself. At the same time, conventional coding processes do not take into account information carried out by content descriptors. Content descriptors are closely related to the content itself, and they potentially can be used to exploit redundancy in entropy coding processes. Embedding content descriptors in the bitstream can reduce content description extraction load, and at the same time, it can reduce the rate associated to the compressed content and its description. In this paper an effective implementation of this approach is presented, where image descriptors are actively used in the coding process for exploiting redundancy. First of all, image areas containing faces are detected and encoded using a scalable method, where the base layer is represented by the corresponding eigenface, and the enhancement layer is formed by the prediction error. The remaining areas are then encoded by using a traditional approach. Simulations show that achievable compression performances are comparable with those provided by conventional, making the proposed approach very convenient for source coding and content description.partially_openpartially_openBoschetti A.; Adami N.; Leonardi R.; Okuda M.Boschetti, Alberto; Adami, Nicola; Leonardi, Riccardo; Okuda, M

    Validation instruments for health promotion in the community pharmacy setting

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    The developments during the past fifty years have resulted in a complete shift in the role of the community pharmacist from that of mainly compounding of medicines to becoming an advisor on health-related issues (Schaefer, 1998). This shift resulted in highlighting the intervention of the pharmacist as the initial contact point for the provision of primary health care. An initiative undertaken in the United Kingdom in 1995, 'Pharmacy in a New Age', identified health promotion as one of the areas that community pharmacists should focus more on (Royal Pharmaceutical Society of Great Britain, 1996). In this day and age of cost containment. evidence-based practice is required to confirm the provision of professional services, including the provision of health promotion (Rupp, 1997). This prompted the development of the Validation Method for Community Pharmacy, which is a process carried out to confirm the effectiveness of the pharmacist in the community setting (Azzopardi, 2000).peer-reviewe
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