78 research outputs found
External validation of anti-Müllerian hormone based prediction of live birth in assisted conception
<p>Background - Chronological age and oocyte yield are independent determinants of live birth in assisted conception. Anti-Müllerian hormone (AMH) is strongly associated with oocyte yield after controlled ovarian stimulation. We have previously assessed the ability of AMH and age to independently predict live birth in an Italian assisted conception cohort. Herein we report the external validation of the nomogram in 822 UK first in vitro fertilization (IVF) cycles.</p>
<p>Methods - Retrospective cohort consisting of 822 patients undergoing their first IVF treatment cycle at Glasgow Centre for Reproductive Medicine. Analyses were restricted to women aged between 25 and 42 years of age. All women had an AMH measured prior to commencing their first IVF cycle. The performance of the model was assessed; discrimination by the area under the receiver operator curve (ROCAUC) and model calibration by the predicted probability versus observed probability.</p>
<p>Results - Live births occurred in 29.4% of the cohort. The observed and predicted outcomes showed no evidence of miscalibration (p = 0.188). The ROCAUC was 0.64 (95% CI: 0.60, 0.68), suggesting moderate and similar discrimination to the original model. The ROCAUC for a continuous model of age and AMH was 0.65 (95% CI 0.61, 0.69), suggesting that the original categories of AMH were appropriate.</p>
<p>Conclusions - We confirm by external validation that AMH and age are independent predictors of live birth. Although the confidence intervals for each category are wide, our results support the assessment of AMH in larger cohorts with detailed baseline phenotyping for live birth prediction.</p>
External validation of anti-Müllerian hormone based prediction of live birth in assisted conception
External validation of anti-M??llerian hormone based prediction of live birth
in assisted conceptio
Compact groups in theory and practice -- IV. The connection to large-scale structure
We investigate the properties of photometrically-selected compact groups
(CGs) in the Sloan Digital Sky Survey. In this paper, the fourth in a series,
we focus on understanding the characteristics of our observed CG sample with
particular attention paid to quantifying and removing contamination from
projected foreground or background galaxies. Based on a simple comparison of
pairwise redshift likelihoods, we find that approximately half of compact
groups in the parent sample contain one or more projected (interloping)
members; our final clean sample contains 4566 galaxies in 1086 compact groups.
We show that half of the remaining CGs are associated with rich groups (or
clusters), i.e. they are embedded sub-structure. The other half have spatial
distributions and number-density profiles consistent with the interpretation
that they are either independently distributed structures within the field
(i.e. they are isolated) or associated with relatively poor structures.
Comparisons of late-type and red-sequence fractions in radial annuli show that
galaxies around apparently isolated compact groups resemble the field
population by 300 to 500 kpc from the group centre. In contrast, the galaxy
population surrounding embedded compact groups appears to remain distinct from
the field out beyond 1 to 2 Mpc, consistent with results for rich groups. We
take this as additional evidence that the observed distinction between compact
groups, i.e. isolated vs. embedded, is a separation between different host
environments.Comment: 15 pages, 11 figures. Accepted for publication in MNRA
The relationship between anti-mullerian hormone in women receiving fertility assessments and age at menopause in subfertile women: evidence from large population studies
<p>Context: Anti-Müllerian hormone (AMH) concentration reflects ovarian aging and is argued to be a useful predictor of age at menopause (AMP). It is hypothesized that AMH falling below a critical threshold corresponds to follicle depletion, which results in menopause. With this threshold, theoretical predictions of AMP can be made. Comparisons of such predictions with observed AMP from population studies support the role for AMH as a forecaster of menopause.</p>
<p>Objective: The objective of the study was to investigate whether previous relationships between AMH and AMP are valid using a much larger data set.</p>
<p>Setting: AMH was measured in 27 563 women attending fertility clinics.</p>
<p>Study Design: From these data a model of age-related AMH change was constructed using a robust regression analysis. Data on AMP from subfertile women were obtained from the population-based Prospect-European Prospective Investigation into Cancer and Nutrition (Prospect-EPIC) cohort (n = 2249). By constructing a probability distribution of age at which AMH falls below a critical threshold and fitting this to Prospect-EPIC menopausal age data using maximum likelihood, such a threshold was estimated.</p>
<p>Main Outcome: The main outcome was conformity between observed and predicted AMP.</p>
<p>Results: To get a distribution of AMH-predicted AMP that fit the Prospect-EPIC data, we found the critical AMH threshold should vary among women in such a way that women with low age-specific AMH would have lower thresholds, whereas women with high age-specific AMH would have higher thresholds (mean 0.075 ng/mL; interquartile range 0.038–0.15 ng/mL). Such a varying AMH threshold for menopause is a novel and biologically plausible finding. AMH became undetectable (<0.2 ng/mL) approximately 5 years before the occurrence of menopause, in line with a previous report.</p>
<p>Conclusions: The conformity of the observed and predicted distributions of AMP supports the hypothesis that declining population averages of AMH are associated with menopause, making AMH an excellent candidate biomarker for AMP prediction. Further research will help establish the accuracy of AMH levels to predict AMP within individuals.</p>
Galaxy Pairs in the Sloan Digital Sky Survey I: Star Formation, AGN Fraction, and the Luminosity/Mass-Metallicity Relation
(Abridged). We present a sample of 1716 galaxies with companions within Delta
v < 500 km/s, r_p < 80 kpc and stellar mass ratio 0.1 < M_1/M_2 < 10 from the
Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4). In agreement with
previous studies, we find an enhancement in the star formation rate (SFR) of
galaxy pairs at projected separations < 30--40 kpc. In addition, we find that
this enhancement is highest (and extends to the greatest separations) for
galaxies of approximately equal mass, the so-called `major' pairs. However, SFR
enhancement can still be detected for a sample of galaxy pairs whose masses are
within a factor of 10 of each other. In agreement with the one previous study
of the luminosity-metallicity (LZ) relation in paired galaxies, we find an
offset to lower metallicities (by ~ 0.1 dex) for a given luminosity for
galaxies in pairs compared to the control sample. We also present the first
mass-metallicity (MZ) relation comparison between paired galaxies and the
field, and again find an offset to lower metallicities (by ~ 0.05 dex) for a
given mass. The smaller offset in the MZ relation indicates that both higher
luminosities and lower metallicities may contribute to the shift of pairs
relative to the control in the LZ relation. We show that the offset in the LZ
relation depends on galaxy half light radius, r_h. Galaxies with r_h < 3 kpc
and with a close companion show a 0.05-0.1 dex downwards offset in metallicity
compared to control galaxies of the same size. Finally, we study the AGN
fraction in both the pair and control sample and find that whilst selecting
galaxies in different cuts of color and asymmetry yields different AGN
fractions, the fraction for pairs and the control sample are consistent for a
given set of selection criteria.Comment: Accepted for publication in the Astronomical Journa
The ATLAS3D project - XXIX : The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images
Date of Acceptance: 25/09/2014Galactic archaeology based on star counts is instrumental to reconstruct the past mass assembly of Local Group galaxies. The development of new observing techniques and data reduction, coupled with the use of sensitive large field of view cameras, now allows us to pursue this technique in more distant galaxies exploiting their diffuse low surface brightness (LSB) light. As part of the ATLAS3D project, we have obtained with the MegaCam camera at the Canada-France-Hawaii Telescope extremely deep, multiband images of nearby early-type galaxies (ETGs). We present here a catalogue of 92 galaxies from the ATLAS3D sample, which are located in low- to medium-density environments. The observing strategy and data reduction pipeline, which achieve a gain of several magnitudes in the limiting surface brightness with respect to classical imaging surveys, are presented. The size and depth of the survey are compared to other recent deep imaging projects. The paper highlights the capability of LSB-optimized surveys at detecting new prominent structures that change the apparent morphology of galaxies. The intrinsic limitations of deep imaging observations are also discussed, among those, the contamination of the stellar haloes of galaxies by extended ghost reflections, and the cirrus emission from Galactic dust. The detection and systematic census of fine structures that trace the present and past mass assembly of ETGs are one of the prime goals of the project. We provide specific examples of each type of observed structures - tidal tails, stellar streams and shells - and explain how they were identified and classified. We give an overview of the initial results. The detailed statistical analysis will be presented in future papers.Peer reviewedFinal Accepted Versio
The Maunakea Spectroscopic Explorer Book 2018
(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is
intended as a concise reference guide to all aspects of the scientific and
technical design of MSE, for the international astronomy and engineering
communities, and related agencies. The current version is a status report of
MSE's science goals and their practical implementation, following the System
Conceptual Design Review, held in January 2018. MSE is a planned 10-m class,
wide-field, optical and near-infrared facility, designed to enable
transformative science, while filling a critical missing gap in the emerging
international network of large-scale astronomical facilities. MSE is completely
dedicated to multi-object spectroscopy of samples of between thousands and
millions of astrophysical objects. It will lead the world in this arena, due to
its unique design capabilities: it will boast a large (11.25 m) aperture and
wide (1.52 sq. degree) field of view; it will have the capabilities to observe
at a wide range of spectral resolutions, from R2500 to R40,000, with massive
multiplexing (4332 spectra per exposure, with all spectral resolutions
available at all times), and an on-target observing efficiency of more than
80%. MSE will unveil the composition and dynamics of the faint Universe and is
designed to excel at precision studies of faint astrophysical phenomena. It
will also provide critical follow-up for multi-wavelength imaging surveys, such
as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field
Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation
Very Large Array.Comment: 5 chapters, 160 pages, 107 figure
Characterising galaxy groups: spectroscopic observations of the Shakhbazyan sample
Groups of galaxies are the most common cosmic structures. However, due to the
poor statistics, projection effects and the lack of accurate distances, our
understanding of their dynamical and evolutionary status is still limited. This
is particularly true for the so called Shakhbazyan groups (SHK) which are still
largely unexplored due to the lack of systematic spectroscopic studies of both
their member galaxies and the surrounding environment. In our previous paper,
we investigated the statistical properties of a large sample of SHK groups
using Sloan Digital Sky Survey data and photometric redshifts. Here we present
the follow-up of 5 SHK groups (SHK 10, 71, 75, 80, 259) observed within our
spectroscopic campaign with the Telescopio Nazionale Galileo, aimed at
confirming their physical reality and strengthening our photometric results.
For each of the selected groups we were able to identify between 6 and 13
spectroscopic members, thus confirming the robustness of the photometric
redshift approach in identifying real galaxy over-densities. Consistently with
the finding of our previous paper, the structures studied here have properties
spanning from those of compact and isolated groups to those of loose groups.
For what the global physical properties are concerned (total mass,
mass-to-light ratios, etc.), we find systematic differences with those reported
in the literature by previous studies. Our analysis suggests that previous
results should be revisited; we show in fact that, if the literature data are
re-analysed in a consistent and homogeneous way, the properties obtained are in
agreement with those estimated for our sample.Comment: 31 pages, 25 figures, 10 tables. Accepted for publication on MNRAS.
Table references updated. Few minor corrections to the text applie
The Pristine survey -- XXIII. Data Release 1 and an all-sky metallicity catalogue based on Gaia DR3 BP/RP spectro-photometry
We use the spectro-photometric information of ~219 million stars from Gaia's
DR3 to calculate synthetic, narrow-band, metallicity-sensitive CaHK magnitudes
that mimic the observations of the Pristine survey, a survey of photometric
metallicities of Milky Way stars that has been mapping more than 6,500 deg^2 of
the northern sky with the CFHT since 2015. These synthetic magnitudes are used
for an absolute re-calibration of the deeper Pristine photometry and, combined
with broadband Gaia information, synthetic and Pristine CaHK magnitudes are
used to estimate photometric metallicities over the whole sky. The resulting
metallicity catalogue is accurate down to [Fe/H]~-3.5 and is particularly
suited for the exploration of the metal-poor Milky Way ([Fe/H]<-1.0). We make
available here the catalogue of synthetic CaHK_syn magnitudes for all stars
with BP/RP information in Gaia DR3, as well as an associated catalogue of more
than ~30 million photometric metallicities for high S/N FGK stars. This paper
further provides the first public DR of the Pristine catalogue in the form of
higher quality recalibrated Pristine CaHK magnitudes and photometric
metallicities for all stars in common with the BP/RP information in Gaia DR3.
We demonstrate that, when available, the much deeper Pristine data greatly
enhances the quality of the derived metallicities, in particular at the faint
end of the catalogue (G_BP>16). Combined, both catalogues include more than 2
million metal-poor star candidates as well as more than 200,000 and ~8,000 very
and extremely metal-poor candidates. Finally, we show that these metallicity
catalogues can be used efficiently, among other applications, for Galactic
archaeology, to hunt for the most metal-poor stars, and to study how the
structure of the Milky Way varies with metallicity, from the flat distribution
of disk stars to the spheroid-shaped metal-poor halo. (Shortened)Comment: 30 pages, 24 figures, submitted to A&A. First two authors are
co-first author. The CaHK photometry catalogue and the two photometric
metallicity catalogues are available, before acceptance, as large compressed
csv files at: https://seafile.unistra.fr/d/ee0c0f05719d4368bcbb
Study protocol of European Fans in Training (EuroFIT):a four-country randomised controlled trial of a lifestyle program for men delivered in elite football clubs
Background: Lifestyle interventions targeting physical activity, sedentary time and dietary behaviours have the potential to initiate and support behavioural change and result in public health gain. Although men have often been reluctant to engage in such lifestyle programs, many are at high risk of several chronic conditions. We have developed an evidence and theory-based, gender sensitised, health and lifestyle program (European Fans in Training (EuroFIT)), which is designed to attract men through the loyalty they feel to the football club they support. This paper describes the study protocol to evaluate the effectiveness and cost-effectiveness of the EuroFIT program in supporting men to improve their level of physical activity and reduce sedentary behaviour over 12 months. Methods: The EuroFIT study is a pragmatic, two-arm, randomised controlled trial conducted in 15 football clubs in the Netherlands, Norway, Portugal and the UK (England). One-thousand men, aged 30 to 65 years, with a self-reported Body Mass Index (BMI) ≥27 kg/m2 will be recruited and individually randomised. The primary outcomes are objectively-assessed changes in total physical activity (steps per day) and total sedentary time (minutes per day) at 12 months after baseline assessment. Secondary outcomes are weight, BMI, waist circumference, resting systolic and diastolic blood pressure, cardio-metabolic blood biomarkers, food intake, self-reported physical activity and sedentary time, wellbeing, self-esteem, vitality and quality of life. Cost-effectiveness will be assessed and a process evaluation conducted. The EuroFIT program will be delivered over 12 weekly, 90-minute sessions that combine classroom discussion with graded physical activity in the setting of the football club. Classroom sessions provide participants with a toolbox of behaviour change techniques to initiate and sustain long-term lifestyle changes. The coaches will receive two days of training to enable them to create a positive social environment that supports men in engaging in sustained behaviour change. Discussion: The EuroFIT trial will provide evidence on the effectiveness and cost-effectiveness of the EuroFIT program delivered by football clubs to their male fans, and will offer insight into factors associated with success in making sustained changes to physical activity, sedentary behaviour, and secondary outcomes, such as diet.Trial registration: ISRCTN: 81935608. Registered 16 June 2015.<br/
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