176,674 research outputs found
Fast and Tiny Structural Self-Indexes for XML
XML document markup is highly repetitive and therefore well compressible
using dictionary-based methods such as DAGs or grammars. In the context of
selectivity estimation, grammar-compressed trees were used before as synopsis
for structural XPath queries. Here a fully-fledged index over such grammars is
presented. The index allows to execute arbitrary tree algorithms with a
slow-down that is comparable to the space improvement. More interestingly,
certain algorithms execute much faster over the index (because no decompression
occurs). E.g., for structural XPath count queries, evaluating over the index is
faster than previous XPath implementations, often by two orders of magnitude.
The index also allows to serialize XML results (including texts) faster than
previous systems, by a factor of ca. 2-3. This is due to efficient copy
handling of grammar repetitions, and because materialization is totally
avoided. In order to compare with twig join implementations, we implemented a
materializer which writes out pre-order numbers of result nodes, and show its
competitiveness.Comment: 13 page
Financial Development and Income Inequality: A Panel Data Approach
We analyze the link between financial development and income inequality for a broad unbalanced dataset of up to 138 developed and developing countries over the years 1960 to 2008. Using credit-to-GDP as a measure of financial development, our results reject theoretical models predicting a negative impact of financial development on income inequality measured by the Gini coefficient. Controlling for country fixed effects and GDP per capita, we find that financial development has a positive effect on income inequality. These results are robust to different measures of financial development, econometric specifications, and control variables.financial development, income inequality, global, panel analysis
Financial Contagion and the European Debt Crisis
Since the beginning of 2010, the Euro Area faces a severe sovereign debt crisis, now generally known as the Euro Crisis. While the Euro Crisis has its origin in Greece, problems have now spread to several other European countries as well. Dynamic conditional correlation models (DCC) are estimated in order to assess if contagious effects are identifiable during the Euro Crisis, or if the countries’ problems are instead due to fundamental problems in the affected economies. Our findings show that there is contagion within the Euro Area. Additionally, contagious effects generated by rating announcements are documented. These results are crucial when it comes to choosing the correct measure and timing of policy intervention.contagion, DCC, Euro Crisis
Cooling in the shade of warped transition disks
The mass of the gaseous reservoir in young circumstellar disks is a crucial
initial condition for the formation of planetary systems, but estimates vary by
orders of magnitude. In some disks with resolvable cavities, sharp inner disk
warps cast two-sided shadows on the outer rings; can the cooling of the gas as
it crosses the shadows bring constraints on its mass? The finite cooling
timescale should result in dust temperature decrements shifted ahead of the
optical/IR shadows in the direction of rotation. However, some systems show
temperature drops, while others do not. The depth of the drops and the
amplitude of the shift depend on the outer disk surface density Sigma through
the extent of cooling during the shadow crossing time, and also on the
efficiency of radiative diffusion. These phenomena may bear observational
counterparts, which we describe with a simple one-dimensional model. An
application to the HD142527 disk suggests an asymmetry in its shadows, and
predicts a >~10deg shift for a massive gaseous disk, with peak Sigma > 8.3
g/cm2. Another application to the DoAr44 disk limits the peak surface density
to Sigma < 13g/cm2Comment: accepted to MNRAS Letter
Penguin amplitudes in hadronic B decays: NLO spectator scattering
We present results on the NLO (alpha_s^2) spectator-scattering corrections to
the topological penguin amplitudes for charmless hadronic two-body B-decays in
QCD factorization. The corrections can be sizable for the colour-suppressed
electroweak penguin amplitudes alpha_{4,EW}^p but otherwise are numerically
small. Our results explicitly demonstrate factorization at this order. To
assess the phenomenological viability of the framework, we consider
penguin-to-tree ratios in the penguin-dominated pi K system and find agreement
to the expected precision (i.e., a power correction).Comment: 4 pages, 2 figures, talk given at ICHEP 2006, 26 July - 2 August,
Mosco
Scissor equivalence for torus links
This article is about a natural distance function induced by smooth
cobordisms between links. We show that the cobordism distance of torus links is
determined by the profiles of their signature functions, up to a constant
factor.Comment: 15 pages, 5 figures, Theorem 1 adde
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