2,460 research outputs found
Heuristics and political accountability in complex governance: An experimental test:
A growing body of empirical work suggests that identifying the actors formally tasked with implementing policy can focus attention away from incumbent politicians. We examine the effects on blame attribution and voting intention of (a) the identifiability of a responsible policy worker (administrator), and (b) the evaluability of the policy work or outcome (policy failure), in the context of programs at two federal agencies (loans by the Small Business Administration and inspections by the U.S. Department of Agriculture). Using a set of online survey experiments with 1105 US adults, we find that the evaluability of a (negative) outcome generally reduces voting intention, but that the identifiability of a policy worker (administrator) tends to shift blame away from the incumbent politician and thus to increase voting intention. These experimental findings provide at least partial support for our theoretical expectations
How Brexit can give Scotland, Wales and Northern Ireland more policymaking power
As the result of last week's election begins to sink in, one thing on the minds of politicians in Scotland, Wales and Northern Ireland is the fate of devolved authority after Brexit. Anthony M. Bertelli (Bocconi and Penn State) asks how Brexit can give them more policymaking power. Prime Minister Boris Johnson endorsed devolved authority during a September trip to Scotland: “We are going to maximise the power of the North. And we are going to make sure that it is people here who are in control over the things that matter to them.” Michael Russell, Scotland’s Secretary for Government Business and Constitutional Relations, saw things differently. He claimed that Westminster is “determined” to roll back devolution in favour of a “more centralised state.
The Many Possible Interpretations of Microlensing Event OGLE-2002-BLG-055
Microlensing event OGLE-2002-BLG-055 is characterized by a smooth, slightly
asymmetric single-lens curve with an isolated, secure data point that is ~0.6
magnitudes brighter than neighboring points separated by a few days. It was
previously suggested that the single deviant data point and global asymmetry
were best explained by a planetary companion to the primary lens with mass
ratio log(q)=-3 to -2, and parallax effects induced by the motion of the Earth.
We revisit the interpretation of OGLE-2002-BLG-055, and show that the data can
be explained by wide variety of models. We find that the deviant data point can
be fit by a large number of qualitatively different binary-lens models whose
mass ratios range, at the ~3-sigma level, from log(q) ~ -4 to -1. This range is
consistent with a planet, brown dwarf, or M-dwarf companion for reasonable
primary masses of M> 0.8 M_sun. A subset of these binary-lens fits consist of a
family of continuously degenerate models whose mass ratios differ by an
order-of-magnitude, but whose light curves differ by <2% for the majority of
the perturbation. The deviant data point can also explained by a binary
companion to the source with secondary/primary flux ratio of ~1%. This model
has the added appeal that the global asymmetry is naturally explained by the
acceleration of the primary induced by the secondary. The binary-source model
yields a measurement of the Einstein ring radius projected on source plane of
\hat r_E=1.87 +/- 0.40 AU. OGLE-2002-BLG-055 is an extreme example that
illustrates the difficulties and degeneracies inherent in the interpretation of
weakly perturbed and/or poorly sampled microlensing light curves.Comment: 8 pages, 3 figures, 1 table. Minor changes. Accepted to ApJ, to
appear in the August 10, 2004 issue (v611
The Near-Infrared Photometric Properties of Bright Giants in the Central Regions of the Galactic Bulge
Images recorded through broad (J, H, K), and narrow (CO, and 2.2micron
continuum) band filters are used to investigate the photometric properties of
bright (K < 13.5) stars in a 6 x 6 arcmin field centered on the SgrA complex.
The giant branch ridgelines in the (K, J-K) and (K, H-K) color-magnitude
diagrams are well matched by the Baade's Window (BW) M giant sequence if the
mean extinction is A_K ~ 2.8 mag. Extinction measurements for individual stars
are estimated using the M_K versus infrared color relations defined by M giants
in BW, and the majority of stars have A_K between 2.0 and 3.5 mag. The
extinction is locally high in the SgrA complex, where A_K ~ 3.1 mag.
Reddening-corrected CO indices, CO_o, are derived for over 1300 stars with J,
H, and K brightnesses, and over 5300 stars with H and K brightnesses. The
distribution of CO_o values for stars with K_o between 11.25 and 7.25 can be
reproduced using the M_K versus CO_o relation defined by M giants in BW. The
data thus suggest that the most metal-rich giants in the central regions of the
bulge and in BW have similar photometric properties and 2.3micron CO strengths.
Hence, it appears that the central region of the bulge does not contain a
population of stars that are significantly more metal-rich than what is seen in
BW.Comment: 29 pages, including 14 figure
The Stellar Populations of NGC 3109: Another Dwarf Irregular Galaxy with a Population II Stellar Halo
We have obtained V and I-band photometry for about 17500 stars in the field
of the dwarf irregular galaxy NGC3109, located in the outskirts of the Local
Group. The photometry allows us to study the stellar populations present inside
and outside the disk of this galaxy. From the VI color-magnitude diagram we
infer metallicities and ages for the stellar populations in the main body and
in the halo of NGC3109. The stars in the disk of this galaxy have a wide
variety of ages, including very young stars with approximately 10^7 yr. Our
main result is to establish the presence of a halo consisting of population II
stars, extending out to about 4.5 arcmin (or 1.8 kpc) above and below the plane
of this galaxy. For these old stars we derive an age of > 10 Gyr and a
metallicity of [Fe/H] = -1.8 +/- 0.2. We construct a deep luminosity function,
obtaining an accurate distance modulus (m-M)_0 = 25.62 +/- 0.1 for this galaxy
based on the I-magnitude of the red giant branch (RGB) tip and adopting E(V-I)
= 0.05.Comment: Accepted for publication in the Astronomical Journal 23 pages, latex,
12 Figures (Fig 1 not available in electronic format
The visual orbits of the spectroscopic binaries HD 6118 and HD 27483 from the Palomar Testbed Interferometer
We present optical interferometric observations of two double-lined
spectroscopic binaries, HD 6118 and HD 27483, taken with the Palomar Testbed
Interferometer (PTI) in the K band. HD 6118 is one of the most eccentric
spectroscopic binaries and HD 27483 a spectroscopic binary in the Hyades open
cluster. The data collected with PTI in 2001-2002 allow us to determine
astrometric orbits and when combined with the radial velocity measurements
derive all physical parameters of the systems. The masses of the components are
2.65 +/- 0.27 M_Sun and 2.36 +/- 0.24 M_Sun for HD 6118 and 1.38 +/- 0.13 M_Sun
and 1.39 +/- 0.13 M_Sun for HD 27483. The apparent semi-major axis of HD 27483
is only 1.2 mas making it the closest binary successfully observed with an
optical interferometer.Comment: submitted to Ap
The Peak Brightness and Spatial Distribution of AGB Stars Near the Nucleus of M32
The bright stellar content near the center of the Local Group elliptical
galaxy M32 is investigated with 0.12 arcsec FWHM H and K images obtained with
the Gemini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving
near the tip of the asymptotic giant branch (AGB), are resolved to within 2
arcsec of the nucleus, and it is concluded that the peak stellar brightness
near the center of M32 is similar to that in the outer regions of the galaxy.
Moreover, the projected density of bright AGB stars follows the visible light
profile to within 2 arcsec of the nucleus, indicating that the brightest stars
are well mixed throughout the galaxy. Thus, there is no evidence for an age
gradient, and the radial variations in spectroscopic indices and ultraviolet
colors that have been detected previously must be due to metallicity and/or
some other parameter. We suggest that either the bright AGB stars formed as
part of a highly uniform and coherent galaxy-wide episode of star formation, or
they originated in a separate system that merged with M32.Comment: 9 pages of text, 3 figures. ApJ (Letters) in pres
Clues on the evolution of the Carina dwarf spheroidal galaxy from the color distribution of its red giant stars
The thin red giant branch (RGB) of the Carina dwarf spheroidal galaxy appears
at first sight quite puzzling and seemingly in contrast with the presence of
several distinct bursts of star formation. In this Letter, we provide a
measurement of the color spread of red giant stars in Carina based on new BVI
wide-field observations, and model the width of the RGB by means of synthetic
color-magnitude diagrams. The measured color spread, Sigma{V-I}=0.021 +/-
0.005, is quite naturally accounted for by the star-formation history of the
galaxy. The thin RGB appears to be essentially related to the limited age range
of its dominant stellar populations, with no need for a metallicity dispersion
at a given age. This result is relatively robust with respect to changes in the
assumed age-metallicity relation, as long as the mean metallicity over the
galaxy lifetime matches the observed value ([Fe/H] = -1.91 +/- 0.12 after
correction for the age effects). This analysis of photometric data also sets
some constraints on the chemical evolution of Carina by indicating that the
chemical abundance of the interstellar medium in Carina remained low throughout
each episode of star formation even though these episodes occurred over many
Gyr.Comment: 4 pages, 3 figures, accepted for publication in the Astrophysical
Journal Letter
Esperienze di didattica della fisica in diversi livelli del sistema educativo
The growing interest of people in science events, the projects supported by
the Italian Ministry of Education, University and Research to foster STEM
teaching in different levels of the education system and the introduction of
modern physics in some Italian high schools, contributed to the strengthening
of interaction between schools, universities and research centers. This
interaction realized in dedicated activities characterized by innovative
communication and education strategies.This paper presents the events of
science dissemination organized in the last years by the University of Ferrara
and the National Institute for Nuclear Physics taking into account some case
study differentiated by contents, recipients and education strategies.Comment: The article is written in Italia
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