4,733 research outputs found
The Tilt of the Fundamental Plane: Three-quarters Structural Nonhomology, One-quarter Stellar Population
The variation of the mass-to-light ratios M/L of early type galaxies as
function of their luminosities L is investigated. It is shown that the tilt
beta=0.27 (in the B--band) of the fundamental plane relation M/L ~ L^{beta} can
be understood as a combination of two effects: about one-quarter (i.e. dbeta
=0.07) is a result of systematic variations of the stellar population
properties with increasing luminosity. The remaining three-quarters (i.e. dbeta
=0.2) can be completely attributed to nonhomology effects that lead to a
systematic change of the surface brightness profiles with increasing
luminosity. Consequently, the observed tilt in the K-band (beta=0.17) where
stellar population effects are negligible, is explained by nonhomology effects
alone. After correcting for nonhomology, the mean value of the mass-to-light
ratio of elliptical galaxies (M/L_B) is 7.1+-2.8 (1 sigma scatter).Comment: 8 pages, 3 figures, ApJL, 600, 39, minor changes made to match the
published versio
Removal processes for tributyltin during municipal wastewater treatment
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2013 Springer.The fate and behaviour of tributyltin (TBT) at two wastewater treatment works was examined. Both sites had two inlet streams, and each utilised high rate biological filters (biofilters) on one the streams, before treatment of the combined flows on trickling filters, with one having additional tertiary processes, installed to remove ammonia and solids. The study was designed to determine if these processes enhanced the removal of TBT. Degradation of TBT was observed in one of the biofilters, possibly as a result of temperature and hydraulic loading. At the treatment works with tertiary processes, the mass flux showed the overall removal of TBT was 68 %, predominantly due to removal with solids in the primary settlement processes. However, overall removal of 95 % was observed in the conventional trickling filter works with 94 % of this due to biodegradation in the trickling filter. The two works both removed TBT, but at different treatment stages and by different processes. Differences in the form (solubility) of TBT in the influent may have attributed to this, although further understanding of factors controlling degradation would allow for a more complete assessment of the potential of biological processes to remove hazardous compounds from wastewaters.United Utilities PL
Stellar populations of classical and pseudo-bulges for a sample of isolated spiral galaxies
In this paper we present the stellar population synthesis results for a
sample of 75 bulges in isolated spiral Sb-Sc galaxies, using the spectroscopic
data from the Sloan Digital Sky Survey and the STARLIGHT code. We find that
both pseudo-bulges and classical bulges in our sample are predominantly
composed of old stellar populations, with mean mass-weighted stellar age around
10 Gyr. While the stellar population of pseudo-bulges is, in general, younger
than that of classical bulges, the difference is not significant, which
indicates that it is hard to distinguish pseudo-bulges from classical bulges,
at least for these isolated galaxies, only based on their stellar populations.
Pseudo-bulges have star formation activities with relatively longer timescale
than classical bulges, indicating that secular evolution is more important in
this kind of systems. Our results also show that pseudo-bulges have a lower
stellar velocity dispersion than their classical counterparts, which suggests
that classical bulges are more dispersion-supported than pseudo-bulges.Comment: 10 pages, 8 figures. Accepted for publication in Astrophysics & Space
Scienc
Holographic formula for the determinant of the scattering operator in thermal AdS
A 'holographic formula' expressing the functional determinant of the
scattering operator in an asymptotically locally anti-de Sitter(ALAdS) space
has been proposed in terms of a relative functional determinant of the scalar
Laplacian in the bulk. It stems from considerations in AdS/CFT correspondence
of a quantum correction to the partition function in the bulk and the
corresponding subleading correction at large N on the boundary. In this paper
we probe this prediction for a class of quotients of hyperbolic space by a
discrete subgroup of isometries. We restrict to the simplest situation of an
abelian group where the quotient geometry describes thermal AdS and also the
non-spinning BTZ instanton. The bulk computation is explicitly done using the
method of images and the answer can be encoded in a (Patterson-)Selberg
zeta-function.Comment: 11 pages, published JPA versio
Holonomies, anomalies and the Fefferman-Graham ambiguity in AdS3 gravity
Using the Chern-Simon formulation of (2+1) gravity, we derive, for the
general asymptotic metrics given by the Fefferman-Graham-Lee theorems, the
emergence of the Liouville mode associated to the boundary degrees of freedom
of (2+1) dimensional anti de Sitter geometries. Holonomies are described
through multi-valued gauge and Liouville fields and are found to algebraically
couple the fields defined on the disconnected components of spatial infinity.
In the case of flat boundary metrics, explicit expressions are obtained for the
fields and holonomies. We also show the link between the variation under
diffeomorphisms of the Einstein theory of gravitation and the Weyl anomaly of
the conformal theory at infinity.Comment: LaTeX, 26 pages, 1 figure, modified version that will appear in Nucl.
Phys.
Beyond MFV in family symmetry theories of fermion masses
Minimal Flavour Violation (MFV) postulates that the only source of flavour
changing neutral currents and CP violation, as in the Standard Model, is the
CKM matrix. However it does not address the origin of fermion masses and mixing
and models that do usually have a structure that goes well beyond the MFV
framework. In this paper we compare the MFV predictions with those obtained in
models based on spontaneously broken (horizontal) family symmetries, both
Abelian and non-Abelian. The generic suppression of flavour changing processes
in these models turns out to be weaker than in the MFV hypothesis. Despite
this, in the supersymmetric case, the suppression may still be consistent with
a solution to the hierarchy problem, with masses of superpartners below 1 TeV.
A comparison of FCNC and CP violation in processes involving a variety of
different family quantum numbers should be able to distinguish between various
family symmetry models and models satisfying the MFV hypothesis.Comment: 34 pages, no figure
First Irish pregnancies after IVF with gestational carrier
In this report, our early experience with screening, monitoring and coordinating IVF utilising gestational carrier treatment is described. Although congenital and iatrogenic etiologies for uterine factor infertility manifest distinctly different reasons for considering a gestational carrier approach, we outline a unified management strategy for both conditions. One patient had congenital absence of the uterus and proximal vagina (Mayer-Rokitansky-Kuster-Hauser syndrome variant), while another patient presented post-hysterectomy and adjuvant brachytherapy for invasive squamous cervical carcinoma. Conception was established for both patients, the first pregnancies to be achieved using an IVF/gestational carrier technique in Ireland. As demonstrated here, selected patients with at least one intact ovary who suffer from uterine factor infertility can be excellent candidates for IVF with embryo transfer to a carefully screened gestational carrier. The role of individual and group counselling is reviewed; professional legal advice is prudent in complex cases
Blastocyst transfer for multiple prior IVF failure: a five year descriptive study
Patients with recurrent IVF failure are generally regarded as having a poor prognosis, and when female age exceeds 35yrs such patients face a particularly bleak outlook. This study reported on blastocyst transfer (BT) performed over a five-year interval in patients seeking “second opinion” after multiple failed IVF cycles. Clinical features and reproductive outcomes were compared between two sets of poor-prognosis IVF patients undergoing BT for the first time, the initial group underwent treatment in 2002 (n=66) and a second group presented five years later (n=392). The two clinical sets had no patients in common. The 2002 group had an average of 3.5(±1.1) prior failed IVF cycles at baseline, and mean (±SD) patient age was 36.4(±3.9)yrs. Average number of oocytes retrieved in this group was 10.4(±5.3) with a fertilisation rate of 58.8%. Although embryo arrest resulted in no transfer for 19 patients (28.8%), clinical pregnancy was achieved for 59.6% of transfers. Five years later, 392 patients underwent BT, but this group had an average of 4.5(±2.3) prior failed IVF cycles. Mean (±SD) female age was 36.0(±3.9)yrs, and the average number of oocytes retrieved in this group was 9.1(±5.4); the fertilisation rate was 59.5%. No blastocysts were available for transfer in 99 cases (25.3%); clinical pregnancy was achieved for 50.0% of transfers. The number of blastocysts transferred was similar in the two groups (1.6 vs. 1.3; p=0.06); the twinning rate rose slightly from 8.2% to 15.1% (p=0.12) despite an increased utilisation of single embryo transfer in 2007 (19.7% vs. 22.2%; p=0.40). Comparisons from 2002 and 2007 found no important differences between the two patient groups, except for a significantly higher rate of prior failed cycles in the 2007 group (
Uniqueness of the asymptotic AdS3 geometry
We explicitly show that in (2+1) dimensions the general solution of the
Einstein equations with negative cosmological constant on a neigbourhood of
timelike spatial infinity can be obtained from BTZ metrics by coordinate
transformations corresponding geometrically to deformations of their spatial
infinity surface. Thus, whatever the topology and geometry of the bulk, the
metric on the timelike extremities is BTZ.Comment: LaTeX, 8 pages, no figures, version that will appear in Class. Quant.
Gra
Inspiratory muscle training reduces blood lactate concentration during volitional hyperpnoea
Although reduced blood lactate concentrations ([lac−]B) have been observed during whole-body exercise following inspiratory muscle training (IMT), it remains unknown whether the inspiratory muscles are the source of at least part of this reduction. To investigate this, we tested the hypothesis that IMT would attenuate the increase in [lac−]B caused by mimicking, at rest, the breathing pattern observed during high-intensity exercise. Twenty-two physically active males were matched for 85% maximal exercise minute ventilation (V˙Emax) and divided equally into an IMT or a control group. Prior to and following a 6 week intervention, participants performed 10 min of volitional hyperpnoea at the breathing pattern commensurate with 85% V˙Emax
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