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Were Presolar Grains Destroyed by the Nebular Process Responsible for the Volatile Element Fractionation?
We present SiC abundances from a number of CM and CR chondrites using NanoSIMS raster ion imaging of acid residues. We find higher SiC abundances for CRs than previously estimated based on noble gases
Effects of final expenditures on ICT goods and services on the croatian domestic output and importsâthe input- output approach
Information and Communication Technology (ICT) has a significant role in the growth and development of almost every national economy. The aim of this paper is to estimate the overall contribution of final expenditures on ICT goods and services on the domestic output and imports of Croatia in terms of gross value added (GVA) and employment. In order to quantify the direct, indirect and induced effects of final expenditures on ICT goods and services to the overall Croatian economy, input-output (IO) analysis is applied. The results of the empirical analysis show that of all three categories of total final uses, the final consumption expenditure on ICT goods and services recorded the highest total contribution in terms of GVA and in terms of employment. The final consumption expenditure of households had the most important role in generating GVA and employment, while the impact of government and non-profit organisations serving households expenditures was limited. At the activity section level, the majority of GVA and the number of jobs were generated in the activity section JâInformation and Communication. The total number of employees induced by final expenditures on goods and services produced by the ICT sectors is estimated at 2.8%. The ICT sectors contributed to the total Croatian GVA in a range higher than 4.5
Can a Logarithmically Running Coupling Mimic a String Tension?
It is shown that a Coulomb potential using a running coupling slightly
modified from the perturbative form can produce an interquark potential that
appears nearly linear over a large distance range. Recent high-statistics SU(2)
lattice gauge theory data fit well to this potential without the need for a
linear string-tension term. This calls into question the accuracy of string
tension measurements which are based on the assumption of a constant
coefficient for the Coulomb term. It also opens up the possibility of obtaining
an effectively confining potential from gluon exchange alone.Comment: 13 pages, LaTeX, two figures not included, available from author.
revision - Line lengths fixed so it will tex properl
Relating jet structure to photometric variability: the Herbig Ae star HD 163296
Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded
by circumstellar dust disks. Some are observed to produce jets, whose
appearance as a sequence of shock fronts (knots) suggests a past episodic
outflow variability. This "jet fossil record" can be used to reconstruct the
outflow history. We present the first optical to near-infrared (NIR)
VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We
determine physical conditions in the knots, as well as their kinematic "launch
epochs". Knots are formed simultaneously on either side of the disk, with a
regular interval of ~16 yr. The velocity dispersion versus jet velocity and the
energy input are comparable in both lobes. However, the mass loss rate,
velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1,
consistent with magneto-centrifugal jet launching models. No evidence for dust
is found in the high-velocity jet, suggesting it is launched within the
sublimation radius (<0.5 au). The jet inclination measured from proper motions
and radial velocities confirms it is perpendicular to the disk. A tentative
relation is found between the structure of the jet and the photometric
variability of the source. Episodes of NIR brightening were previously detected
and attributed to a dusty disk wind. We report for the first time significant
optical fadings lasting from a few days up to a year, coinciding with the NIR
brightenings. These are likely caused by dust lifted high above the disk plane;
this supports the disk wind scenario. The disk wind is launched at a larger
radius than the high-velocity atomic jet, although their outflow variability
may have a common origin. No significant relation between outflow and accretion
variability could be established. Our findings confirm that this source
undergoes periodic ejection events, which may be coupled with dust ejections
above the disk plane.Comment: 20 pages, 11 figures, accepted for publication in Astronomy &
Astrophysic
High-Contrast NIR Polarization Imaging of MWC480
One of the key predictions of modeling from the IR excess of Herbig Ae stars
is that for protoplanetary disks, where significant grain growth and settling
has occurred, the dust disk has flattened to the point that it can be partially
or largely shadowed by the innermost material at or near the dust sublimation
radius. When the self-shadowing has already started, the outer disk is expected
to be detected in scattered light only in the exceptional cases that the scale
height of the dust disk at the sublimation radius is smaller than usual.
High-contrast imaging combined with the IR spectral energy distribution allow
us to measure the degree of flattening of the disk, as well as to determine the
properties of the outer disk. We present polarimetric differential imaging in
band obtained with Subaru/HiCIAO of one such system, MWC 480. The HiCIAO
data were obtained at a historic minimum of the NIR excess. The disk is
detected in scattered light from 0\farcs2-1\farcs0 (27.4-137AU). Together with
the marginal detection of the disk from 1998 February 24 by HST/NICMOS, our
data constrain the opening half angle for the disk to lie between
1.3. When compared with similar measures in CO for
the gas disk from the literature, the dust disk subtends only 30% of the
gas disk scale height (H/R0.03). Such a dust disk is a factor of 5-7
flatter than transitional disks, which have structural signatures that giant
planets have formed.Comment: 21 pages, 6 figures, 1 table, ApJ accepted 2012-05-0
Parents\u27 Goals: An Analysis of Therapist Reasoning
Purpose:
Illustrate the use of DDDM to develop parent-identified goals for occupational therapy and to identify underlying sensory integration factors hypothesized to be impacting participation
Constituting monetary conservatives via the 'savings habit': New Labour and the British housing market bubble
The ongoing world credit crunch might well kill off the most recent bubble dynamics in the British housing market by driving prices systematically downwards from their 2007 peak. Nonetheless, the experience of that bubble still warrants analytical attention. The Labour Government might not have been responsible for consciously creating it, but it has certainly grasped the opportunities the bubble has provided in an attempt to enforce a process of agential change at the heart of the British economy. The key issue in this respect is the way in which the Government has challenged the legitimacy of passive welfare receipts in favour of establishing a welfare system based on incorporating the individual into an active asset-holding society. The housing market has taken on new political significance as a means for individuals first to acquire assets and then to accumulate wealth on the back of asset ownership. The ensuing integration of the housing market into an increasingly reconfigured welfare system has permeated into the politics of everyday life. It has been consistent with individuals remaking their political subjectivities in line with preferences for the type of conservative monetary policies that typically keep house price bubbles inflated
Constructive links between some morphological hierarchies on edge-weighted graphs
International audienceIn edge-weighted graphs, we provide a unified presentation of a family of popular morphological hierarchies such as component trees, quasi flat zones, binary partition trees, and hierarchical watersheds. For any hierarchy of this family, we show if (and how) it can be obtained from any other element of the family. In this sense, the main contribution of this paper is the study of all constructive links between these hierarchies
Influence of aging on the neural correlates of autobiographical, episodic, and semantic memory retrieval
We used fMRI to assess the neural correlates of autobiographical, semantic, and episodic memory retrieval in healthy young and older adults. Participants were tested with an eventrelated paradigm in which retrieval demand was the only factor varying between trials. A spatio-temporal partial least square analysis was conducted to identify the main patterns of activity characterizing the groups across conditions. We identified brain regions activated by all three memory conditions relative to a control condition. This pattern was expressed equally in both age groups and replicated previous findings obtained in a separate group of younger adults. We also identified regions whose activity differentiated among the different memory conditions. These patterns of differentiation were expressed less strongly in the older adults than in the young adults, a finding that was further confirmed by a barycentric discriminant analysis. This analysis showed an age-related dedifferentiation in autobiographical and episodic memory tasks but not in the semantic memory task or the control condition. These findings suggest that the activation of a common memory retrieval network is maintained with age, whereas the specific aspects of brain activity that differ with memory content are more vulnerable and less selectively engaged in older adults. Our results provide a potential neural mechanism for the well-known age differences in episodic/autobiographical memory, and preserved semantic memory, observed when older adults are compared with younger adults
Structure and evolution of debris disks around F-type stars: I. Observations, database and basic evolutionary aspects
Although photometric and spectroscopic surveys with the Spitzer Space
Telescope increased remarkably the number of well studied debris disks around
A-type and Sun-like stars, detailed analyzes of debris disks around F-type
stars remained less frequent. Using the MIPS camera and the IRS spectrograph we
searched for debris dust around 82 F-type stars with Spitzer. We found 27 stars
that harbor debris disks, nine of which are new discoveries. The dust
distribution around two of our stars, HD 50571 and HD 170773, was found to be
marginally extended on the 70um MIPS images. Combining the MIPS and IRS
measurements with additional infrared and submillimeter data, we achieved
excellent spectral coverage for most of our debris systems. We have modeled the
excess emission of 22 debris disks using a single temperature dust ring model
and of 5 debris systems with two-temperature models. The latter systems may
contain two dust rings around the star. In accordance with the expected trends,
the fractional luminosity of the disks declines with time, exhibiting a decay
rate consistent with the range of model predictions. We found the distribution
of radial dust distances as a function of age to be consistent with the
predictions of both the self stirred and the planetary stirred disk evolution
models. A more comprehensive investigation of the evolution of debris disks
around F-type stars, partly based on the presented data set, will be the
subject of an upcoming paper.Comment: Accepted for publication in ApJS, 42 pages, 18 figures, 8 tables
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