10,640 research outputs found

    The Euro changeover and price adjustments in Italy

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    By estimating a staggered price model over the period 1980q1-2010q2, this paper documents that, after the euro changeover, Italian retailers have increased the number of price adjustments, which has translated into a higher inflation rate, with a detrimental effect on the competitiveness of the Italian economy

    Orbit decidability and the conjugacy problem for some extensions of groups

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    Given a short exact sequence of groups with certain conditions, 1→F→G→H→11\to F\to G\to H\to 1, we prove that GG has solvable conjugacy problem if and only if the corresponding action subgroup A⩽Aut(F)A\leqslant Aut(F) is orbit decidable. From this, we deduce that the conjugacy problem is solvable, among others, for all groups of the form Z2⋊Fm\mathbb{Z}^2\rtimes F_m, F2⋊FmF_2\rtimes F_m, Fn⋊ZF_n \rtimes \mathbb{Z}, and Zn⋊AFm\mathbb{Z}^n \rtimes_A F_m with virtually solvable action group A⩽GLn(Z)A\leqslant GL_n(\mathbb{Z}). Also, we give an easy way of constructing groups of the form Z4⋊Fn\mathbb{Z}^4\rtimes F_n and F3⋊FnF_3\rtimes F_n with unsolvable conjugacy problem. On the way, we solve the twisted conjugacy problem for virtually surface and virtually polycyclic groups, and give an example of a group with solvable conjugacy problem but unsolvable twisted conjugacy problem. As an application, an alternative solution to the conjugacy problem in Aut(F2)Aut(F_2) is given

    SR-FTiR microscopy and FTIR imaging in the earth sciences

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    During the last decades, several books have been devoted to the application of spectroscopic methods in mineralogy. Several short courses and meetings have addressed particular aspects of spectroscopy, such as the analysis of hydrous components in minerals and Earth materials. In these books, complete treatment of the infrared theory and practical aspects of instrumentation and methods, along with an exhaustive list of references, can be found. The present chapter is intended to cover those aspects of infrared spectroscopy that have been developed in the past decade and are not included in earlier reviews such as Volume 18 of Reviews in Mineralogy. These new topics involve primarily: (1) the use of synchrotron radiation (SR), which, although not a routine method, is now rather extensively applied in infrared studies, in particular those requiring ultimate spatial and time resolution and the analysis of extremely small samples (a few tens of micrometers); (2) the development of imaging techniques also for foreseen time resolved studies of geo-mineralogical processes and environmental studies.Comment: 36 pages, 24 figures - Reviews in Mineralogy & Geochemistry - Vol. 78 (2013) in pres

    Dust formation around AGB and SAGB stars: a trend with metallicity?

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    We calculate the dust formed around AGB and SAGB stars of metallicity Z=0.008 by following the evolution of models with masses in the range 1M<M<8M throughthe thermal pulses phase, and assuming that dust forms via condensation of molecules within a wind expanding isotropically from the stellar surface. We find that, because of the strong Hot Bottom Burning (HBB) experienced, high mass models produce silicates, whereas lower mass objects are predicted to be surrounded by carbonaceous grains; the transition between the two regimes occurs at a threshold mass of 3.5M. These fndings are consistent with the results presented in a previous investigation, for Z=0.001. However, in the present higher metallicity case, the production of silicates in the more massive stars continues for the whole AGB phase, because the HBB experienced is softer at Z=0.008 than at Z=0.001, thus the oxygen in the envelope, essential for the formation of water molecules, is never consumed completely. The total amount of dust formed for a given mass experiencing HBB increases with metallicity, because of the higher abundance of silicon, and the softer HBB, both factors favouring a higher rate of silicates production. This behaviour is not found in low mass stars,because the carbon enrichment of the stellar surface layers, due to repeated Third Drege Up episodes, is almost independent of the metallicity. Regarding cosmic dust enrichment by intermediate mass stars, we find that the cosmic yield at Z=0.008 is a factor 5 larger than at Z=0.001. In the lower metallicity case carbon dust dominates after about 300 Myr, but at Z=0.008 the dust mass is dominated by silicates at all times,with a prompt enrichment occurring after about 40 Myr, associated with the evolution of stars with masses M =7.5 -8M.Comment: 14 pages, 10 figures, 2 Tables, accepted for publication in MNRA
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