11,860 research outputs found

    Photometric redshifts and selection of high redshift galaxies in the NTT and Hubble Deep Fields

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    We present and compare in this paper new photometric redshift catalogs of the galaxies in three public fields: the NTT Deep Field, the HDF-N and the HDF-S. Photometric redshifts have been obtained for thewhole sample, by adopting a χ2\chi^2 minimization technique on a spectral library drawn from the Bruzual and Charlot synthesis models, with the addition of dust and intergalactic absorption. The accuracy, determined from 125 galaxies with known spectroscopic redshifts, is σz∼0.08(0.3)\sigma_z\sim 0.08 (0.3) in the redshift intervals z=0−1.5(1.5−3.5)z=0-1.5 (1.5-3.5). The global redshift distribution of I-selected galaxies shows a distinct peak at intermediate redshifts, z~0.6 at I_{AB}<26 and z~0.8 at I_{AB}<27.5 followed by a tail extending to z~6. We also present for the first time the redshift distribution of the total IR-selected sample to faint limits (Ks≤21Ks \leq 21 and J≤22J\leq22). It is found that the number density of galaxies at 1.25<z<1.5 is ~ 0.1 /arcmin^22 at J<=21 and ~1./arcmin^2} at J<22, and drops to 0.3/arcmin^2 (at J<22) at 1.5<z<2. The HDFs data sets are used to compare the different results from color selection criteria and photometric redshifts in detecting galaxies in the redshift range 3.5<z<4.5 Photometric redshifts predict a number of high z candidates in both the HDF-N and HDF-S that is nearly 2 times larger than color selection criteria, and it is shown that this is primarily due to the inclusion of dusty models that were discarded in the original color selection criteria by Madau et al 1998. In several cases, the selection of these objects is made possible by the constraints from the IR bands. Finally, it is shown that galactic M stars may mimic z>5 candidates in the HDF filter set and that the 4 brightest candidates at z>5z>5 in the HDF-S are indeed most likely M stars. (ABRIDGED)Comment: Version accepted on July, 20, 2000. To appear on Astronomical Journal, Nov 2000. The data and photometric redshift catalogs presented here are available on line at http://www.mporzio.astro.it/HIGH

    ¿Modifican el PSA los licopenos de la dieta y exógenos?

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    El objetivo del presente artículo es describir la historia alimentaria y la composición corporal de pacientes con alto riesgo de padecer cáncer de próstata (CAP) y observar la influencia de la suplementación con licopeno sobre el PSA de la misma población.Fil: López Laur, José Daniel. Universidad Nacional de Cuyo. Facultad de Ciencias MédicasFil: López Fontana, C.. Universidad Nacional de Cuyo. Facultad de Ciencias MédicasFil: López Fontana, G.. Universidad Nacional de Cuyo. Facultad de Ciencias MédicasFil: López Fontana, R.. Universidad Nacional de Cuyo. Facultad de Ciencias Médica

    Stress corrosion cracking of titanium alloys

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    The effect of hydrogen on the properties of metals, including titanium and its alloys, was investigated. The basic theories of stress corrosion of titanium alloys are reviewed along with the literature concerned with the effect of absorbed hydrogen on the mechanical properties of metals. Finally, the basic modes of metal fracture and their importance to this study is considered. The experimental work was designed to determine the effects of hydrogen concentration on the critical strain at which plastic instability along pure shear directions occurs. The materials used were titanium alloys Ti-8Al-lMo-lV and Ti-5Al-2.5Sn

    Phonon Properties of Knbo3 and Ktao3 from First-Principles Calculations

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    The frequencies of transverse-optical Γ\Gamma phonons in KNbO3_3 and KTaO3_3 are calculated in the frozen-phonon scheme making use of the full-potential linearized muffin-tin orbital method. The calculated frequencies in the cubic phase of KNbO3_3 and in the tetragonal ferroelectric phase are in good agreement with experimental data. For KTaO3_3, the effect of lattice volume was found to be substantial on the frequency of the soft mode, but rather small on the relative displacement patterns of atoms in all three modes of the T1uT_{1u} symmetry. The TO frequencies in KTaO3_3 are found to be of the order of, but somehow higher than, the corresponding frequencies in cubic KNbO3_3.Comment: 8 pages + 1 LaTeX figure, Revtex 3.0, SISSA-CM-94-00

    The Role of Commercial Banks and Financial Intermediaries in the New Consensus Macroeconomics (NCM): A Preliminary and Critical Appraisal of Old and New Models

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    Giuseppe Fontana and Marco Veronese Passarella in this chapter, entitled, ‘Aggregate Demand, Money and Finance in the New Consensus Macroeconomics: a Critical Appraisal’, critically assess the ‘New Consensus Macroeconomics’ (NCM) theory and its recent developments. Building on the Wicksellian ‘two-interest rates model’, the NCM highlights the role of interest rates in the transmission mechanism of monetary policy, whereas monetary aggregates are treated as residual variables. However, in contrast with Wicksell’s theory, banks and financial institutions are usually neglected in the NCM theory. As a result, the financial instability and recurrent banking crises of modern economies have received little attention in modern macroeconomics. This chapter has three main goals. First, it aims to provide a critical analysis of the original NCM model and some recent developments. Second, it aims to show that few amendments to it are sufficient to account for the financial instability and banking crises of real-world economies. Third, it shows that some important policy-making conclusions logically follow once the role of banks, credit and finance is properly taken on board
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