1,396 research outputs found
The determinants of savings in the third pension pillar
The paper analyses participation in and contributions to the third pillar of the pension system by Belgian households. This pillar represents individual saving for retirement and has been growing rapidly. A detailed dataset of tax declarations over the period from 1993 until 2003 was used to analyse the possible determinants of saving in the third pillar. Firstly, this dataset makes an analysis from a macroeconomic point of view possible, showing an apparent increase in total contributions to the third pillar by 39 p.c. in real terms between 1993 and 2003. This increase is mainly due to a rise in the participation rate (29 p.c. in 1993 and 40 p.c. in 2003). A detailed analysis is provided across the age groups, which further shows the influence of the demographic evolution, the average income of the participants in the third pillar and the contribution rate. The dataset also helps point up a wide number of possible microeconomic determinants of saving for retirement, such as age, income, professional status, civil status, region of residence, property ownership, employment situation, participation in second pillar pension schemes, number of dependents, etc. Moreover, the database allows a distinction to be made between the two forms in the third pillar : pension saving and life insurance. From such a microeconomic point of view, the analysis sheds some light on the major determinants of participation to the third pillar. The main findings show that older households are more likely to opt for a third pillar pension scheme. Furthermore, it appears that households consider the two forms of the third pillar as being complementary rather than substitutes for each other : households that participate in pension saving schemes are also more likely to take out life insurance and vice versa. Besides age, the other determinants that have a positive impact on participation in the third pillar of the pension system are : having higher income, being self-employed, getting an early retirement pension, being a home owner, being married and living in Flanders rather than Brussels or Wallonia.personal finance, pension fund, life insurance, private pensions
Partner selection in B2B informational service markets
This study investigates the impact of selection criteria associated with interpersonal interaction (good personal relationships; enriching the service offering with interpretation and advice) on supplier consideration. More specifically, it examines how the importance of these criteria is contingent upon service-related dimensions. An experimental study among client firms in the market research industry that combines a conjoint and a between-subjects design leads to several new insights. First, while good personal relationships play an important role in the selection of a service provider, its impact is increased if the service offering is subjective in nature and decreased if it is strategically important. Second, enriching the service offering with interpretation and advice is more important for subjective as well as for strategically important service offerings. Third, as to other selection criteria, the study results show some interesting differences between consideration and choice. Price has a substantive impact only on choice, while a strong brand name is helpful for the service provider only in the consideration stage
The size-star formation relation of massive galaxies at 1.5<z<2.5
We study the relation between size and star formation activity in a complete
sample of 225 massive (M > 5 x 10^10 Msun) galaxies at 1.5<z<2.5, selected from
the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis
model fits to the observed restframe UV-NIR SEDs, and independent MIPS 24
micron observations, 65% of galaxies are actively forming stars, while 35% are
quiescent. Using sizes derived from 2D surface brightness profile fits to high
resolution (FWHM_{PSF}~0.45 arcsec) groundbased ISAAC data, we confirm and
improve the significance of the relation between star formation activity and
compactness found in previous studies, using a large, complete mass-limited
sample. At z~2, massive quiescent galaxies are significantly smaller than
massive star forming galaxies, and a median factor of 0.34+/-0.02 smaller than
galaxies of similar mass in the local universe. 13% of the quiescent galaxies
are unresolved in the ISAAC data, corresponding to sizes <1 kpc, more than 5
times smaller than galaxies of similar mass locally. The quiescent galaxies
span a Kormendy relation which, compared to the relation for local early types,
is shifted to smaller sizes and brighter surface brightnesses and is
incompatible with passive evolution. The progenitors of the quiescent galaxies,
were likely dominated by highly concentrated, intense nuclear star bursts at
z~3-4, in contrast to star forming galaxies at z~2 which are extended and
dominated by distributed star formation.Comment: 6 pages, 4 figures, accepted for publication in Ap
The Majority of Compact Massive Galaxies at z~2 are Disk Dominated
We investigate the stellar structure of massive, quiescent galaxies at z~2,
based on Hubble Space Telescope/WFC3 imaging from the Early Release Science
program. Our sample of 14 galaxies has stellar masses of M* > 10^{10.8} Msol
and photometric redshifts of 1.5 < z < 2.5. In agreement with previous work,
their half-light radii are <2 kpc, much smaller than equally massive galaxies
in the present-day universe. A significant subset of the sample appears highly
flattened in projection, which implies, considering viewing angle statistics,
that a significant fraction of the galaxies in our sample have pronounced
disks. This is corroborated by two-dimensional surface brightness profile fits.
We estimate that 65% +/- 15% of the population of massive, quiescent z~2
galaxies are disk-dominated. The median disk scale length is 1.5 kpc,
substantially smaller than the disks of equally massive galaxies in the
present-day universe. Our results provide strong observational evidence that
the much-discussed ultra-dense high-redshift galaxies should generally be
thought of as disk-like stellar systems with the majority of stars formed from
gas that had time to settle into a disk.Comment: published versio
The Evolution of the Field and Cluster Morphology-Density Relation for Mass-Selected Samples of Galaxies
The Sloan Digital Sky Survey (SDSS) and photometric/spectroscopic surveys in
the GOODS-South field (the Chandra Deep Field-South, CDFS) are used to
construct volume-limited, stellar mass-selected samples of galaxies at
redshifts 0<z<1. The CDFS sample at 0.6<z<1.0 contains 207 galaxies complete
down to M=4x10^10 Msol (for a ``diet'' Salpeter IMF), corresponding to a
luminosity limit for red galaxies of M_B=-20.1. The SDSS sample at
0.020<z<0.045 contains 2003 galaxies down to the same mass limit, which
corresponds to M_B=-19.3 for red galaxies. Morphologies are determined with an
automated method, using the Sersic parameter n and a measure of the residual
from the model fits, called ``bumpiness'', to distinguish different
morphologies. These classifications are verified with visual classifications.
In agreement with previous studies, 65-70% of the galaxies are located on the
red sequence, both at z~0.03 and at z~0.8. Similarly, 65-70% of the galaxies
have n>2.5. The fraction of E+S0 galaxies is 43+/-3%$ at z~0.03 and 48+/-7% at
z~0.8, i.e., it has not changed significantly since z~0.8. When combined with
recent results for cluster galaxies in the same redshift range, we find that
the morphology-density relation for galaxies more massive than 0.5M* has
remained constant since at least z~0.8. This implies that galaxies evolve in
mass, morphology and density such that the morphology-density relation does not
change. In particular, the decline of star formation activity and the
accompanying increase in the stellar mass density of red galaxies since z~1
must happen without large changes in the early-type galaxy fraction in a given
environment.Comment: 16 pages, 13 figures, 2 tables. Updated to match journal version.
Will appear in ApJ (vol. 670, p. 206
Extensive dissection of the pulmonary artery treated with combined heart–lung transplantation
The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics from 0.7<z<2.7
We present the KMOS^3D survey, a new integral field survey of over 600
galaxies at 0.7<z<2.7 using KMOS at the Very Large Telescope (VLT). The KMOS^3D
survey utilizes synergies with multi-wavelength ground and space-based surveys
to trace the evolution of spatially-resolved kinematics and star formation from
a homogeneous sample over 5 Gyrs of cosmic history. Targets, drawn from a
mass-selected parent sample from the 3D-HST survey, cover the star
formation-stellar mass () and rest-frame planes uniformly. We
describe the selection of targets, the observations, and the data reduction. In
the first year of data we detect Halpha emission in 191
Msun galaxies at z=0.7-1.1 and z=1.9-2.7. In
the current sample 83% of the resolved galaxies are rotation-dominated,
determined from a continuous velocity gradient and , implying
that the star-forming 'main sequence' (MS) is primarily composed of rotating
galaxies at both redshift regimes. When considering additional stricter
criteria, the Halpha kinematic maps indicate at least ~70% of the resolved
galaxies are disk-like systems. Our high-quality KMOS data confirm the elevated
velocity dispersions reported in previous IFS studies at z>0.7. For
rotation-dominated disks, the average intrinsic velocity dispersion decreases
by a factor of two from 50 km/s at z~2.3 to 25 km/s at z~0.9 while the
rotational velocities at the two redshifts are comparable. Combined with
existing results spanning z~0-3, disk velocity dispersions follow an
approximate (1+z) evolution that is consistent with the dependence of velocity
dispersion on gas fractions predicted by marginally-stable disk theory.Comment: 20 pages, 11 figures, 1 Appendix; Accepted to ApJ November 2
The Far-Infrared, UV and Molecular Gas Relation in Galaxies up to z=2.5
We use the infrared excess (IRX) FIR/UV luminosity ratio to study the
relation between the effective UV attenuation (A_IRX) and the UV spectral slope
(beta) in a sample of 450 1<z<2.5 galaxies. The FIR data is from very deep
Herschel observations in the GOODS fields that allow us to detect galaxies with
SFRs typical of galaxies with log(M)>9.3. Thus, we are able to study galaxies
on and even below the main SFR-stellar mass relation (main sequence). We find
that main sequence galaxies form a tight sequence in the IRX--beta plane, which
has a flatter slope than commonly used relations. This slope favors a SMC-like
UV extinction curve, though the interpretation is model dependent. The scatter
in the IRX-beta plane, correlates with the position of the galaxies in the
SFR-M plane. Using a smaller sample of galaxies with CO gas masses, we study
the relation between the UV attenuation and the molecular gas content. We find
a very tight relation between the scatter in the IRX-beta plane and the
specific attenuation (S_A), a quantity that represents the attenuation
contributed by the molecular gas mass per young star. S_A is sensitive to both
the geometrical arrangement of stars and dust, and to the compactness of the
star forming regions. We use this empirical relation to derive a method for
estimating molecular gas masses using only widely available integrated
rest-frame UV and FIR photometry. The method produces gas masses with an
accuracy between 0.12-0.16 dex in samples of normal galaxies between z~0 and
z~1.5. Major mergers and sub-millimeter galaxies follow a different S_A
relation.Comment: 11 pages, 6 pages appendix, 11 figures, accepted to Ap
Structure and star formation in galaxies out to z=3: evidence for surface density dependent evolution and upsizing
We present an analysis of galaxies in the CDF-South. We find a tight relation
to z=3 between color and size at a given mass, with red galaxies being small,
and blue galaxies being large. We show that the relation is driven by stellar
surface density or inferred velocity dispersion: galaxies with high surface
density are red and have low specific star formation rates, and galaxies with
low surface density are blue and have high specific star formation rates.
Surface density and inferred velocity dispersion are better correlated with
specific star formation rate and color than stellar mass. Hence stellar mass by
itself is not a good predictor of the star formation history of galaxies. In
general, galaxies at a given surface density have higher specific star
formation rates at higher redshift. Specifically, galaxies with a surface
density of 1-3 10^9 Msun/kpc^2 are "red and dead" at low redshift,
approximately 50% are forming stars at z=1, and almost all are forming stars by
z=2. This provides direct additional evidence for the late evolution of
galaxies onto the red sequence. The sizes of galaxies at a given mass evolve
like 1/(1+z)^(0.59 +- 0.10). Hence galaxies undergo significant upsizing in
their history. The size evolution is fastest for the highest mass galaxies, and
quiescent galaxies. The persistence of the structural relations from z=0 to
z=2.5, and the upsizing of galaxies imply that a relation analogous to the
Hubble sequence exists out to z=2.5, and possibly beyond. The star forming
galaxies at z >= 1.5 are quite different from star forming galaxies at z=0, as
they have likely very high gas fractions, and star formation time scales
comparable to the orbital time.Comment: 20 pages, accepted for publication in ApJ, 2008, 68
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