72 research outputs found
Photometric Properties of Six Local Volume Dwarf Galaxies from Deep Near-Infrared Observations
We have obtained deep near-infrared - (1.25 m), - (1.65m)
and -band (2.15 m) imaging for a sample of six dwarf galaxies
(M_B\ga-17 mag) in the Local Volume (LV, D\la10 Mpc). The sample consists
mainly of early-type dwarf galaxies found in various environments in the LV.
Two galaxies (LEDA 166099 and UGCA 200) in the sample are detected in the
near-infrared for the first time. The deep near-infrared images allow for a
detailed study of the photometric and structural properties of each galaxy. The
surface brightness profiles of the galaxies are detected down to the ~ isophote in the - and -bands, and in
the -band. The total magnitudes of the galaxies are derived in the three
wavelength bands. For the brightest galaxies (M_B\la-15.5 mag) in the sample,
we find that the Two Micron All Sky Survey (2MASS) underestimates the total
magnitudes of these systems by up to \la0.5 mag. The radial surface
brightness profiles of the galaxies are fitted with an exponential (for those
galaxies having a stellar disk) or S\'ersic law to derive the structure of the
underlying stellar component. In particular, the effective surface brightness
() and effective radius () are determined from the analytic fits to
the surface brightness profile. The - colours for the galaxies have
been measured to explore the luminosity-metallicity relation for early-type
dwarfs. In addition, the - colours of the galaxies are used to assess
their evolutionary state relative to other galaxy morphologies. The total
stellar masses of the dwarf galaxies are derived from the -band photometric
measurements. These will later be compared to the dynamical mass estimates for
the galaxies to determine their dark matter content.Comment: 14 pages, 8 figures, submitted to MNRA
Epistemic Schmagency?
Constructivist approaches in epistemology and ethics offer a promising account of normativity. But constructivism faces a powerful Schmagency Objection, raised by David Enoch. While Enochâs objection has been widely discussed in the context of practical norms, no one has yet explored how the Schmagency Objection might undermine epistemic constructivism. In this paper, I rectify that gap. First, I develop the objection against a prominent form of epistemic constructivism, Belief Constitutivism. Belief Constitutivism is susceptible to a Schmagency Objection, I argue, because it locates the source of normativity in the belief rather than the agent. In the final section, I propose a version of epistemic constructivism that locates epistemic normativity as constitutive of agency. I argue that this version has the resources to respond to the Schmagency Objection
Toxicokinetics of bisphenol-S and its glucuronide in plasma and urine following oral and dermal exposure in volunteers for the interpretation of biomonitoring data
The measurement of bisphenol-S (BPS) and its glucurono-conjugate (BPSG) in urine may be used for the biomonitoring of exposure in populations. However, this requires a thorough knowledge of their toxicokinetics. The time courses of BPS and BPSG were assessed in accessible biological matrices of orally and dermally exposed volunteers. Under the approval of the Research Ethics Committee of the University of Montreal, six volunteers were orally exposed to a BPS-d8 deuterated dose of 0.1 mg/kg body weight (bw). One month later, 1 mg/kg bw of BPS-d8 were applied on 40 cm2 of the forearm and then washed 6 h after application. Blood samples were taken prior to dosing and at fixed time periods over 48 h after treatment; complete urine voids were collected pre-exposure and at pre-established intervals over 72 h postdosing. Following oral exposure, the plasma concentrationâtime courses of BPS-d8 and BPSG-d8 over 48 h evolved in parallel, and showed a rapid appearance and elimination. Average peak values (±SD) were reached at 0.7 ± 0.1 and 1.1 ± 0.4 h postdosing and mean (±SD) apparent elimination half-lives (tÂœ) of 7.9 ± 1.1 and 9.3 ± 7.0 h were calculated from the terminal phase of BPS-d8 and BPSG-d8 in plasma, respectively. The fraction of BPS-d8 reaching the systemic circulation unchanged (i.e. bioavailability) was further estimated at 62 ± 5% on average (±SD) and the systemic plasma clearance at 0.57 ± 0.07 L/kg bw/h. Plasma concentrationâtime courses and urinary excretion rate profiles roughly evolved in parallel for both substances, as expected. The average percent (±SD) of the administered dose recovered in urine as BPS-d8 and BPSG-d8 over the 0â72 h period postdosing was 1.72 ± 1.3 and 54 ± 10%. Following dermal application, plasma levels were under the lower limit of quantification (LLOQ) at most time points. However, peak values were reached between 5 and 8 h depending on individuals, suggesting a slower absorption rate compared to oral exposure. Similarly, limited amounts of BPS-d8 and its conjugate were recovered in urine and peak excretion rates were reached between 5 and 11 h postdosing. The average percent (±SD) of the administered dose recovered in urine as BPS-d8 and BPSG-d8 was about 0.004 ± 0.003 and 0.09 ± 0.07%, respectively. This study provided greater precision on the kinetics of this contaminant in humans and, in particular, evidenced major differences between BPA and BPS kinetics with much higher systemic levels of active BPS than BPA, an observation explained by a higher oral bioavailability of BPS than BPA. These data should also be useful in developing a toxicokinetic model for a better interpretation of biomonitoring data
Are epistemic reasons normative?
According to a widely held view, epistemic reasons are normative reasons for belief â much like prudential or moral reasons are normative reasons for action. In recent years, however, an increasing number of authors have questioned the assumption that epistemic reasons are normative. In this article, I discuss an important challenge for anti-normativism about epistemic reasons and present a number of arguments in support of normativism. The challenge for anti-normativism is to say what kind of reasons epistemic reasons are if they are not normative reasons. I discuss various answers to this challenge and find them all wanting. The arguments for normativism each stress a certain analogy between epistemic reasons and normative reasons for action. Just like normative reasons for action, epistemic reasons provide partial justification; they provide premises for correct reasoning; they constitute good bases for the responses they are reasons for; and they are reasons for which agents can show these responses without committing a mistake. In each case, I argue that the relevant condition is plausibly sufficient for the normativity of a reason, and that normativism is in any case in a much better position to explain the analogy than anti-normativism
Towards a model of talent development in physical education
Traditional conceptions of talent generally emphasise the construction of threshold values and the development of relatively unitary abilities, and this approach still dominates talent development programmes for elite sport. Most researchers on high ability, however, now favour domain-specific, multidimensional conceptions of ability that stress the development of behavioural potential and its interaction with personal and environmental characteristics. This paper presents a model of talent in physical education, drawing together findings from a wide range of literature on the realisation and inhibition of abilities, international studies of effective school-based identification and provision strategies, and a conception of the subject as an integration and realisation of different forms of ability. In presenting this model, the authors aim to redress the imbalance within the current debate from an almost total concern with out-of-school clubs and the preparation for adult elite sport, in favour of a more equitable and inclusive approach, premised upon the unique importance of mainstream, curricular physical education within any talent development scheme
A Survey of Bayesian Statistical Approaches for Big Data
The modern era is characterised as an era of information or Big Data. This
has motivated a huge literature on new methods for extracting information and
insights from these data. A natural question is how these approaches differ
from those that were available prior to the advent of Big Data. We present a
review of published studies that present Bayesian statistical approaches
specifically for Big Data and discuss the reported and perceived benefits of
these approaches. We conclude by addressing the question of whether focusing
only on improving computational algorithms and infrastructure will be enough to
face the challenges of Big Data
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