960 research outputs found
Abstract verification and debugging of constraint logic programs
The technique of Abstract Interpretation [13] has allowed the development of sophisticated program analyses which are provably correct and practical. The semantic approximations produced by such analyses have been traditionally applied to optimization during program compilation. However, recently, novel and promising applications of semantic approximations have been proposed in the more general context of program verification and debugging [3],[10],[7]
The - and -to-stellar mass correlations of late- and early-type galaxies and their consistency with the observational mass functions
We compile and carrefully homogenize local galaxy samples with available
information on stellar, and/or masses, and morphology.
After processing the information on upper limits in the case of non gas
detections, we determine the - and -to-stellar mass
relations and their scatter for both late- and early-type galaxies.
The obtained relations are fitted to single or double power laws. Late-type
galaxies are significantly gas richer than early-type ones, specially at high
masses. The respective -to- mass ratios as a function of
are discussed. Further, we constrain the full mass-dependent
distribution functions of the - and -to-stellar mass ratios.
We find that they can be described by a Schechter function for late types and a
(broken) Schechter + uniform function for early types. By using the observed
galaxy stellar mass function and the volume-complete late-to-early-type galaxy
ratio as a function of , these empirical distribution functions are
mapped into and mass functions. The obtained mass
functions are consistent with those inferred from large surveys. The empirical
gas-to-stellar mass relations and their distributions for local late- and
early-type galaxies presented here can be used to constrain models and
simulations of galaxy evolution.Comment: 43 pages, 18 figures, to appear in RMxAA. Minor corrections
introduced. The presented results are optimal for comparisons with
theoretical predictions. Py-code to generate the HI- and H2-to-stellar mass
relations and their 1sigma scatter, as well as the full mass-dependent
distribution functions of the MHI/Ms and MH2/Ms ratios are available upon
request to A.R. Calett
The bivariate gas-stellar mass distributions and the mass functions of early- and late-type galaxies at
We report the bivariate HI- and H-stellar mass distributions of local
galaxies in addition of an inventory of galaxy mass functions, MFs, for HI,
H, cold gas, and baryonic mass, separately into early- and late-type
galaxies. The MFs are determined using the HI and H conditional
distributions and the galaxy stellar mass function, GSMF. For the conditional
distributions we use the compilation presented in Calette et al. 2018. For
determining the GSMF from to
, we combine two spectroscopic samples from the SDSS at the redshift
range . We find that the low-mass end slope of the GSMF, after
correcting from surface brightness incompleteness, is ,
consistent with previous determinations. The obtained HI MFs agree with radio
blind surveys. Similarly, the H MFs are consistent with CO follow-up
optically-selected samples. We estimate the impact of systematics due to
mass-to-light ratios and find that our MFs are robust against systematic
errors. We deconvolve our MFs from random errors to obtain the intrinsic MFs.
Using the MFs, we calculate cosmic density parameters of all the baryonic
components. Baryons locked inside galaxies represent 5.4% of the universal
baryon content, while % of the HI and H mass inside galaxies reside
in late-type morphologies. Our results imply cosmic depletion times of H
and total neutral H in late-type galaxies of and 7.2 Gyr,
respectively, which shows that late type galaxies are on average inefficient in
converting H into stars and in transforming HI gas into H. Our results
provide a fully self-consistent empirical description of galaxy demographics in
terms of the bivariate gas--stellar mass distribution and their projections,
the MFs. This description is ideal to compare and/or to constrain galaxy
formation models.Comment: 37 pages, 17 figures. Accepted for publication in PASA. A code that
displays tables and figures with all the relevant statistical distributions
and correlations discussed in this paper is available here
https://github.com/arcalette/Python-code-to-generate-Rodriguez-Puebla-2020-result
Relationship between downwelling surface shortwave radiative fluxes and sea surface temperature over the tropical Pacific: AMIP II models versus satellite estimates
Incident shortwave radiation at the Earth's surface is the driving force of the climate system. Understanding the relationship between this forcing and the sea surface temperature, in particular, over the tropical Pacific Ocean is a topic of great interest because of possible climatic implications. The objective of this study is to investigate the relationship between downwelling shortwave radiative fluxes and sea surface temperature by using available data on radiative fluxes. We assess first the shortwave radiation from three General Circulation Models that participated in the second phase of the Atmospheric Model Intercomparison Project (AMIP II) against estimates of such fluxes from satellites. The shortwave radiation estimated from the satellite is based on observations from the International Satellite Cloud Climatology Project D1 data and the University of Maryland Shortwave Radiation Budget model (UMD/SRB). Model and satellite estimates of surface radiative fluxes are found to be in best agreement in the central equatorial Pacific, according to mean climatology and spatial correlations. We apply a Canonical Correlation Analysis to determine the interrelated areas where shortwave fluxes and sea surface temperature are most sensitive to climate forcing. Model simulations and satellite estimates of shortwave fluxes both capture well the interannual signal of El Niño-like variability. The tendency for an increase in shortwave radiation from the UMD/SRB model is not captured by the AMIP II models
Exploiting Term Hiding to Reduce Run-time Checking Overhead
One of the most attractive features of untyped languages is the flexibility
in term creation and manipulation. However, with such power comes the
responsibility of ensuring the correctness of these operations. A solution is
adding run-time checks to the program via assertions, but this can introduce
overheads that are in many cases impractical. While static analysis can greatly
reduce such overheads, the gains depend strongly on the quality of the
information inferred. Reusable libraries, i.e., library modules that are
pre-compiled independently of the client, pose special challenges in this
context. We propose a technique which takes advantage of module systems which
can hide a selected set of functor symbols to significantly enrich the shape
information that can be inferred for reusable libraries, as well as an improved
run-time checking approach that leverages the proposed mechanisms to achieve
large reductions in overhead, closer to those of static languages, even in the
reusable-library context. While the approach is general and system-independent,
we present it for concreteness in the context of the Ciao assertion language
and combined static/dynamic checking framework. Our method maintains the full
expressiveness of the assertion language in this context. In contrast to other
approaches it does not introduce the need to switch the language to a (static)
type system, which is known to change the semantics in languages like Prolog.
We also study the approach experimentally and evaluate the overhead reduction
achieved in the run-time checks.Comment: 26 pages, 10 figures, 2 tables; an extension of the paper version
accepted to PADL'18 (includes proofs, extra figures and examples omitted due
to space reasons
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