3,473 research outputs found
Language in Economics and Accounting Research: The Role of Linguistic History
This paper investigates whether a consideration of linguistic history is important when studying the relationship between economic and linguistic behaviors. Several recent economic studies have suggested that differences between languages can affect the way people think and behave (linguistic relativity or SapirâWhorf hypothesis). For example, the way a language obliges one to talk about the future might influence intertemporal decisions, such as a companyâs earnings management. However, languages have historical relations that lead to shared featuresâthey do not constitute independent observations. This can inflate correlations between variables if not dealt with appropriately (Galtonâs problem). We discuss this problem and provide an overview of the latest methods to control linguistic history. We then provide an empirical demonstration of how Galtonâs problem can bias results in an investigation of whether a companyâs earnings management behavior is predicted by structural features of its employeesâ language. We find a strong relationship when not controlling linguistic history, but the relationship disappears when controls are applied. In contrast, economic predictors of earnings management remain robust. Overall, our results suggest that careful consideration of linguistic history is important for distinguishing true causes from spurious correlations in economic behaviors
Magma production and growth of the lava dome of the Soufriere Hills Volcano, Montserrat, West Indies: November 1995 to November 1997
Proton Drip-Line Calculations and the Rp-process
One-proton and two-proton separation energies are calculated for proton-rich
nuclei in the region . The method is based on Skyrme Hartree-Fock
calculations of Coulomb displacement energies of mirror nuclei in combination
with the experimental masses of the neutron-rich nuclei. The implications for
the proton drip line and the astrophysical rp-process are discussed. This is
done within the framework of a detailed analysis of the sensitivity of rp
process calculations in type I X-ray burst models on nuclear masses. We find
that the remaining mass uncertainties, in particular for some nuclei with
, still lead to large uncertainties in calculations of X-ray burst light
curves. Further experimental or theoretical improvements of nuclear mass data
are necessary before observed X-ray burst light curves can be used to obtain
quantitative constraints on ignition conditions and neutron star properties. We
identify a list of nuclei for which improved mass data would be most important.Comment: 20 pages, 9 figures, 2 table
Understanding local ethnic inequalities in childhood BMI through cross-sectional analysis of routinely collected local data
The Millennium Run Observatory: First Light
Simulations of galaxy evolution aim to capture our current understanding as
well as to make predictions for testing by future experiments. Simulations and
observations are often compared in an indirect fashion: physical quantities are
estimated from the data and compared to models. However, many applications can
benefit from a more direct approach, where the observing process is also
simulated and the models are seen fully from the observer's perspective. To
facilitate this, we have developed the Millennium Run Observatory (MRObs), a
theoretical virtual observatory which uses virtual telescopes to `observe'
semi-analytic galaxy formation models based on the suite of Millennium Run dark
matter simulations. The MRObs produces data that can be processed and analyzed
using the standard software packages developed for real observations. At
present, we produce images in forty filters from the rest-frame UV to IR for
two stellar population synthesis models, three different models of IGM
absorption, and two cosmologies (WMAP1/7). Galaxy distributions for a large
number of mock lightcones can be `observed' using models of major ground- and
space-based telescopes. The data include lightcone catalogues linked to
structural properties of galaxies, pre-observation model images, mock telescope
images, and Source Extractor products that can all be traced back to the higher
level dark matter, semi-analytic galaxy, and lightcone catalogues available in
the Millennium database. Here, we describe our methods and announce a first
public release of simulated surveys (e.g., SDSS, CFHT-LS, GOODS, GOODS/ERS,
CANDELS, and HUDF). The MRObs browser, an online tool, further facilitates
exploration of the simulated data. We demonstrate the benefits of a direct
approach through a number of example applications (galaxy number counts in
CANDELS, clusters, morphologies, and dropout selections).Comment: MNRAS, in press. Millennium Run Observatory data products, online
tools, and more available through http://galformod.mpa-garching.mpg.de/mrobs
Local stochastic non-Gaussianity and N-body simulations
Large-scale clustering of highly biased tracers of large-scale structure has
emerged as one of the best observational probes of primordial non-Gaussianity
of the local type (i.e. f_{NL}^{local}). This type of non-Gaussianity can be
generated in multifield models of inflation such as the curvaton model.
Recently, Tseliakhovich, Hirata, and Slosar showed that the clustering
statistics depend qualitatively on the ratio of inflaton to curvaton power \xi
after reheating, a free parameter of the model. If \xi is significantly
different from zero, so that the inflaton makes a non-negligible contribution
to the primordial adiabatic curvature, then the peak-background split ansatz
predicts that the halo bias will be stochastic on large scales. In this paper,
we test this prediction in N-body simulations. We find that large-scale
stochasticity is generated, in qualitative agreement with the prediction, but
that the level of stochasticity is overpredicted by ~30%. Other predictions,
such as \xi independence of the halo bias, are confirmed by the simulations.
Surprisingly, even in the Gaussian case we do not find that halo model
predictions for stochasticity agree consistently with simulations, suggesting
that semi-analytic modeling of stochasticity is generally more difficult than
modeling halo bias.Comment: v3: minor changes matching published versio
The Beginning and Evolution of the Universe
We review the current standard model for the evolution of the Universe from
an early inflationary epoch to the complex hierarchy of structure seen today.
We summarize and provide key references for the following topics: observations
of the expanding Universe; the hot early Universe and nucleosynthesis; theory
and observations of the cosmic microwave background; Big Bang cosmology;
inflation; dark matter and dark energy; theory of structure formation; the cold
dark matter model; galaxy formation; cosmological simulations; observations of
galaxies, clusters, and quasars; statistical measures of large-scale structure;
and measurement of cosmological parameters. We conclude with discussion of some
open questions in cosmology. This review is designed to provide a graduate
student or other new worker in the field an introduction to the cosmological
literature.Comment: 69 pages. Invited review article for Publications of the Astronomical
Society of the Pacific. Supplementary references, tables, and more concise
PDF file at http://www.physics.drexel.edu/univers
The Bimodal Galaxy Stellar Mass Function in the COSMOS Survey to z~1: A Steep Faint End and a New Galaxy Dichotomy
We present a new analysis of stellar mass functions (MF) in the COSMOS field
to fainter limits than has been previously probed to z~1. Neither the total nor
the passive or star-forming MF can be well fit with a single Schechter function
once one probes below 3e9 Msun. We observe a dip or plateau at masses ~1e10
Msun, and an upturn towards a steep faint-end slope of -1.7 at lower mass at
any z<1. This bimodal nature of the MF is not solely a result of the blue/red
dichotomy. The blue MF is by itself bimodal at z~1. This suggests a new
dichotomy in galaxy formation that predates the appearance of the red sequence.
We propose two interpretations for this bimodality. If the gas fraction
increases towards lower mass, galaxies with M_baryon~1e10 Msun would shift to
lower stellar masses, creating the observed dip. This would indicate a change
in star formation efficiency, perhaps linked to supernovae feedback becoming
much more efficient. Therefore, we investigate whether the dip is present in
the baryonic (stars+gas) MF. Alternatively, the dip could be created by an
enhancement of the galaxy assembly rate at ~1e11 Msun, a phenomenon that
naturally arises if the baryon fraction peaks at M_halo ~1e12 Msun. In this
scenario, galaxies occupying the bump around M* would be identified with
central galaxies and the second fainter component having a steep faint-end
slope with satellites. While the dip is apparent in the total MF at any z, it
appears to shift from the blue to red population, likely as a result of
transforming high-mass blue galaxies into red ones. At the same time, we detect
a drastic upturn in the number of low-mass red galaxies. Their increase with
time reflects a decrease in the number of blue systems and so we tentatively
associate them with satellite dwarf galaxies that have undergone quenching.Comment: 16 pages, 10 figures, accepted for publication in Ap
Evaluation of recruitment methods for a trial targeting childhood obesity: Families for Health randomised controlled trial
Background:
Recruitment to trials evaluating the effectiveness of childhood obesity management interventions is challenging. We report our experience of recruitment to the Families for Health study, a randomised controlled trial evaluating the effectiveness of a family-based community programme for children aged 6â11 years, versus usual care. We evaluated the effectiveness of active recruitment (contacting eligible families directly) versus passive recruitment (informing the community through flyers, public events, media).
Methods:
Initial approaches included passive recruitment via the media (newspapers and radio) and two active recruitment methods: National Child Measurement Programme (letters to families with overweight children) and referrals from health-care professionals. With slow initial recruitment, further strategies were employed, including active (e.g. targeted letters from general practices) and passive (e.g. flyers, posters and public events) methods. At first enquiry from a potential participant, families were asked where they heard about the study. Further quantitative (questionnaire) and qualitative data (one-to-one interviews with parents/carers), were collected from recruited families at baseline and 3-month follow-up and included questions about recruitment.
Results:
In total, 194 families enquired about Families for Health, and 115 (59.3 %) were recruited and randomised. Active recruitment yielded 85 enquiries, with 43 families recruited (50.6 %); passive recruitment yielded 99 enquiries with 72 families recruited (72.7 %). Information seen at schools or GP surgeries accounted for over a quarter of enquiries (28.4 %) and over a third (37.4 %) of final recruitment. Eight out of ten families who enquired this way were recruited. Media-led enquiries were low (5 %), but all were recruited. Children of families recruited actively were more likely to be Asian or mixed race. Despite extensive recruitment methods, the trial did not recruit as planned, and was awarded a no-cost extension to complete the 12-month follow-up.
Conclusions:
The higher number of participants recruited through passive methods may be due to the large number of potential participants these methods reached and because participants may see the information more than once. Recruiting to a child obesity treatment study is complex and it is advisable to use multiple recruitment strategies, some aiming at blanket coverage and some targeted at families with children who are overweight
Artificial drainage of peatlands: hydrological and hydrochemical process and wetland restoration
Peatlands have been subject to artificial drainage for centuries. This drainage has been in response to agricultural demand, forestry, horticultural and energy properties of peat and alleviation of flood risk. However, the are several environmental problems associated with drainage of peatlands. This paper describes the nature of these problems and examines the evidence for changes in hydrological and hydrochemical processes associated with these changes. Traditional black-box water balance approaches demonstrate little about wetland dynamics and therefore the science of catchment response to peat drainage is poorly understood. It is crucial that a more process-based approach be adopted within peatland ecosystems. The environmental problems associated with peat drainage have led, in part, to a recent reversal in attitudes to peatlands and we have seen a move towards wetland restoration. However, a detailed understanding of hydrological, hydrochemical and ecological process-interactions will be fundamental if we are to adequately restore degraded peatlands, preserve those that are still intact and understand the impacts of such management actions at the catchment scale
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