7,772 research outputs found
Sequent and Hypersequent Calculi for Abelian and Lukasiewicz Logics
We present two embeddings of infinite-valued Lukasiewicz logic L into Meyer
and Slaney's abelian logic A, the logic of lattice-ordered abelian groups. We
give new analytic proof systems for A and use the embeddings to derive
corresponding systems for L. These include: hypersequent calculi for A and L
and terminating versions of these calculi; labelled single sequent calculi for
A and L of complexity co-NP; unlabelled single sequent calculi for A and L.Comment: 35 pages, 1 figur
Feeling of knowing and restudy choices
Feeling-of-knowing judgments (FOK-Js) reflect peopleâs confidence that they would be able to recognize a currently unrecallable item. Although much research has been devoted to the factors determining the magnitude and accuracy of FOK-Js, much less work has addressed the issue of whether FOK-Js are related to any form of metacognitive control over memory processes. In the present study, we tested the hypothesis that FOK-Js are related to participantsâ choices of which unrecallable items should be restudied. In three experiments, we showed that participants tend to choose for restudy items with high FOK-Js, both when they are explicitly asked to choose for restudy items that can be mastered in the restudy session (Exps. 1a and 2) and when such specific instructions are omitted (Exp. 1b). The study further demonstrated that increasing FOK-Js via priming cues affects restudy choices, even though it does not affect recall directly. Finally, Experiment 2 showed the strategy of restudying unrecalled items with high FOK-Js to be adaptive, because the efficacy of restudy is greater for these items than for items with low FOK-Js. Altogether, the present findings underscore an important role of FOK-Js for the metacognitive control of study operations
Does individual variation in metabolic phenotype predict fish behaviour and performance?
There is increasing interest in documenting and explaining the existence of marked intraspecific variation in metabolic rate in animals, with fishes providing some of the best-studied examples. After accounting for variation due to other factors, there can typically be a two to three-fold variation among individual fishes for both standard and maximum metabolic rate (SMR and MMR). This variation is reasonably consistent over time (provided that conditions remain stable), and its underlying causes may be influenced by both genes and developmental conditions. In this paper, current knowledge of the extent and causes of individual variation in SMR, MMR and aerobic scope (AS), collectively its metabolic phenotype, is reviewed and potential links among metabolism, behaviour and performance are described. Intraspecific variation in metabolism has been found to be related to other traits: fishes with a relatively high SMR tend to be more dominant and grow faster in high food environments, but may lose their advantage and are more prone to risk-taking when conditions deteriorate. In contrast to the wide body of research examining links between SMR and behavioural traits, very little work has been directed towards understanding the ecological consequences of individual variation in MMR and AS. Although AS can differ among populations of the same species in response to performance demands, virtually nothing is known about the effects of AS on individual behaviours such as those associated with foraging or predator avoidance. Further, while factors such as food availability, temperature, hypoxia and the fish's social environment are known to alter resting and MMRs in fishes, there is a paucity of studies examining how these effects vary among individuals, and how this variation relates to behaviour. Given the observed links between metabolism and measures of performance, understanding the metabolic responses of individuals to changing environments will be a key area for future research because the environment will have a strong influence on which animals survive predation, become dominant and ultimately have the highest reproductive success. Although current evidence suggests that variation in SMR may be maintained within populations via context-dependent fitness benefits, it is suggested that a more integrative approach is now required to fully understand how the environment can modulate individual performance via effects on metabolic phenotypes encompassing SMR, MMR and AS
Passive Evolution: Are the Faint Blue Galaxy Counts Produced by a Population of Eternally Young Galaxies?
A constant age population of blue galaxies, postulated in the model of
Gronwall & Koo (1995), seems to provide an attractive explanation of the excess
of very blue galaxies in the deep galaxy counts. Such a population may be
generated by a set of galaxies with cycling star formation rates, or at the
other extreme, be maintained by the continual formation of new galaxies which
fade after they reach the age specified in the Gronwall and Koo model. For both
of these hypotheses, we have calculated the luminosity functions including the
respective selection criteria, the redshift distributions, and the number
counts in the B_J and K bands. We find a substantial excess in the number of
galaxies at low redshift (0 < z < 0.05) over that observed in the CFH redshift
survey (Lilly et al. 1995) and at the faint end of the Las Campanas luminosity
function (Lin et al. 1996). Passive or mild evolution fails to account for the
deep galaxy counts because of the implications for low redshift determinations
of the I-selected redshift distribution and the r-selected luminosity function
in samples where the faded counterparts of the star-forming galaxies would be
detectable.Comment: 11 pages, LaTeX type (aaspp4.sty), 3 Postscript figures, submitted to
ApJ Letter
The development of an adolescent sporting gendered habitus: Young people's interpretation of UK sports-media coverage of Rio 2016 Olympic Games
Bourdieuâs Theory of Practice explains how institutions â specifically for this paper, sports media â influence the taken-for-granted assumptions of oneâs habitus. Sportswomen receive less media coverage than sportsmen, yet the influence that this has on young people is under-researched. Using a mixed method approach, combining the results of a content and narrative analysis of 2514 articles and 2051 photographs from four UK online media outlets (BBC Sport, The Guardian, Sky Sports News, Twitter Moments) with interviews with 70 young people (33 males and 37 females; aged 15-16 years) from three schools in North East England, this paper explores how sports-media messages are interpreted within the framework of a gendered habitus. Two empirical themes emerged: firstly, young people expect female athletes to be underrepresented and sexualised in sports-media, affecting how sport is constructed as unimportant for females for the accrual of social capital. Secondly, media messages that promote female attractiveness are internalised within young peopleâs habitus. The adolescent gendered habitus is influenced by media messages: the prioritisation of sportsmen leads to young women viewing sport as ânot for themâ. The role of sport within a gendered habitus reflects hegemonic masculinity, promoting sport for men and stereotypical femininity for women
Selection of high-z supernovae candidates
Deep, ground based, optical wide-field supernova searches are capable of
detecting a large number of supernovae over a broad redshift range up to z~1.5.
While it is practically unfeasible to obtain spectroscopic redshifts of all the
supernova candidates right after the discovery, we show that the magnitudes and
colors of the host galaxies, as well as the supernovae, can be used to select
high-z supernova candidates, for subsequent spectroscopic and photometric
follow-up.
Using Monte-Carlo simulations we construct criteria for selecting galaxies in
well-defined redshift bands. For example, with a selection criteria using B-R
and R-I colors we are able to pick out potential host galaxies for which z>0.85
with 80% confidence level and with a selection efficiency of 64-86%. The method
was successfully tested using real observations from the HDF.
Similarly, we show that that the magnitude and colors of the supernova
discovery data can be used to constrain the redshift. With a set of cuts based
on V-R and R-I in a search to m_I~25, supernovae at z~1 can be selected in a
redshift interval sigma_z <0.15.Comment: 33 pages, 13 figures, accepted for publication in PASP (March 2002
issue
New and Old Tests of Cosmological Models and Evolution of Galaxies
We describe the classical cosmological tests, such as the Log-Log,
redshift-magnitude and angular diameter tests, and propose some new tests of
the evolution of galaxies and the universe. Most analyses of these tests treat
the problem in terms of a luminosity function and its evolution which can lead
to incorrect conclusions when dealing with high redshift sources. We develop a
proper treatment in three parts. In the first part we describe these tests
based on the isophotal values of the quantities such as flux, size or surface
brightness. We show the shortcomings of the simple point source approximation
based solely on the luminosity function and consideration of the flux limit. We
emphasize the multivariate nature of the problem and quantify the effects of
other selection biases due to the surface brightness and angular size
limitations. In these considerations the surface brightness profile plays a
critical role. In the second part we show that considerable simplification over
the complicated isophotal scheme is achieved if these test are carried out in
some sort of metric scheme, for example that suggested by Petrosian (1976).
This scheme, however, is limited to well resolved sources. Finally, we describe
the new tests, which use the data to a fuller extent than the isophotal or
metric based tests, and amount to simply counting the pixels or adding their
intensities as a function of the pixel surface brightness, instead of dealing
with surface brightness, sizes and fluxes of individual galaxies. We show that
the data analysis and its comparison with the theoretical models of the
distributions and evolution of galaxies has the simplicity of the metric test
and utilizes the data more fully than the isophotal test.Comment: 29 pages including 8 figures.
http://www-bigbang.stanford.edu/~vahe/papers/finals/newtest.ps. To appear in
ApJ, Oct. 199
The CANADA-FRANCE REDSHIFT SURVEY XIII: The luminosity density and star-formation history of the Universe to z ~ 1
The comoving luminosity density of the Universe is estimated from the CFRS
faint galaxy sample in three wavebands (2800A, 4400A and 1 micron) over the
redshift range 0 < z < 1. In all three wavebands, the comoving luminosity
density increases markedly with redshift. For a (q_0 = 0.5, Omega = 1.0)
cosmological model, the comoving luminosity density increases as at 1 micron, as at 4400A and as at 2800A, these exponents being reduced by 0.43 and 1.12 for (0.05,0.1)
and (-0.85,0.1) cosmological models respectively. The variation of the
luminosity density with epoch can be reasonably well modelled by an actively
evolving stellar population with a Salpeter initial mass function (IMF)
extending to 125 M_sun, a star-formation rate declining with a power 2.5, and a
turn-on of star-formation at early epochs. A Scalo (1986) IMF extending to the
same mass limit produces too many long-lived low mass stars. This rapid
evolution of the star-formation rate and comoving luminosity density of the
Universe is in good agreement with the conclusions of Pei and Fall (1995) from
their analysis of the evolving metallicity of the Universe. One consequence of
this evolution is that the physical luminosity density at short wavelengths has
probably declined by two orders of magnitude since z ~ 1.Comment: uuencoded compressed tar file containing 8 page Tex file, 2
postscript figures and 2 tables. Ap J Letters, in press. Also available at
http://www.astro.utoronto.ca/~lilly/CFRS/papers.htm
The September 11 attacks and their impact on mental distress in the UK
Using a longitudinal household panel dataset in the United Kingdom, where most interviews are conducted in September each year, we are able to show that the attacks of September 11 resulted in higher levels of mental distress for those interviewed after that date in 2001 compared to those interviewed before it. This provides one of the first examples of the impact of a terrorist attack in one country on well-being in another country.Working Pape
Galaxy number counts- IV. surveying the Herschel deep field in the near-infrared
(abridged) We present results from two new near-infrared imaging surveys. One
covers 47.2 arcmin^2 to K(3\sigma)<20 whilst a second, deeper survey covers a
sub-area of 1.8 arcmin^2 to K(3\sigma)<22.75. Over the entire area we have
extremely deep UBRI photometry. Our K- counts are consistent with the
predictions of non-evolving models with 0 < q0 <0.5. The K-selected (B-K)
galaxy colour distributions move sharply bluewards fainter than K~20 and at at
brighter magnitudes (K<20) our observed colour distributions indicate a
deficiency of red, early-type galaxies at z~1 in comparison with passively
evolving models. This implies either a pure luminosity evolution (PLE) model
with a low level of continuing star-formation following an an initial burst, or
dynamical merging. At fainter magnitudes, the continuing bluewards trend
observed in (B-K) can be explained purely in terms of passively evolving PLE
models. Our observed numbers of (I-K)>4 galaxies at K<20 exhibit the same
deficiency, suggesting that at least part of the larger deficit observed in
(B-K) at K<20 may be due to star-formation rather than dynamical merging.
Finally, as we and others have noted, the number-redshift distribution at
18<K<19 of recent, deep K- selected redshift surveys is well fitted by
non-evolving models; passively evolving models with a Salpeter or Scalo initial
mass functions overpredict the numbers of galaxies with z>1. Dynamical merging
is one possible solution to reduce the numbers of these galaxies but a
dwarf-dominated IMF for early-type galaxies could offer an alternative
explanation; we show that this model reproduces both the optical-infrared
colour distributions and the K- band galaxy counts.Comment: 15 pages, 9 figures, revised version, requires astrobib.sty,
mn-abs.sty, submitted to MNRA
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