410 research outputs found

    The SLUGGS survey: the mass distribution in early-type galaxies within five effective radii and beyond

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    We study mass distributions within and beyond 5 effective radii (Re) in 23 early-type galaxies from the SAGES Legacy Unifying Globulars and Galaxies Survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEep Imaging Multi-Object Spectrograph, and consist of line-of-sight velocities for ̃3500 GCs, measured with a high precision of ̃15 km s-1 per GC and extending out to ̃13 Re. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The observed scatter between our mass estimates and results from the literature is less than 0.2 dex. The dark matter fraction within 5 Re (fDM) increases from ̃0.6 to ̃0.8 for low- and high-mass galaxies, respectively, with some intermediate-mass galaxies (M* ̃ 1011 M☉) having low fDM ̃ 0.3, which appears at odds with predictions from simple galaxy models. We show that these results are independent of the adopted orbital anisotropy, stellar mass-to-light (M/L) ratio, and the assumed slope of the gravitational potential. However, the low fDM in the ̃1011 M☉ galaxies agrees with the cosmological simulations of Wu et al. where the pristine dark matter distribution has been modified by baryons during the galaxy assembly process. We find hints that these M* ̃ 1011 M☉ galaxies with low fDM have very diffuse dark matter haloes, implying that they assembled late. Beyond 5 Re, the M/L gradients are steeper in the more massive galaxies and shallower in both low and intermediate mass galaxies

    The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies

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    Due to longer dynamical time-scales, the outskirts of early-type galaxies retain the footprint of their formation and assembly. Under the popular two-phase galaxy formation scenario, an initial in situ phase of star formation is followed by minor merging and accretion of ex situ stars leading to the expectation of observable transitions in the kinematics and stellar populations on large scales. However, observing the faint galactic outskirts is challenging, often leaving the transition unexplored. The large-scale, spatially resolved stellar kinematic data from the SAGES Legacy Unifying Galaxies and GlobularS (SLUGGS) survey are ideal for detecting kinematic transitions. We present kinematic maps out to 2.6 effective radii on average, kinemetry profiles, measurement of kinematic twists and misalignments, and the average outer intrinsic shape of 25 SLUGGS galaxies. We find good overall agreement in the kinematic maps and kinemetry radial profiles with literature. We are able to confirm significant radial modulations in rotational versus pressure support of galaxies with radius so that the central and outer rotational properties may be quite different. We also test the suggestion that galaxies may be more triaxial in their outskirts and find that while fast rotating galaxies were already shown to be axisymmetric in their inner regions, we are unable to rule out triaxiality in their outskirts.We compare our derived outer kinematic information to model predictions from a two-phase galaxy formation scenario. We find that the theoretical range of local outer angular momentum agrees well with our observations, but that radial modulations are much smaller than predicted

    The stellar and sub-stellar IMF of simple and composite populations

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    The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing metallicity and in increasingly massive early-type galaxies. It declines quite steeply below about 0.07Msun with brown dwarfs (BDs) and very low mass stars having their own IMF. The most massive star of mass mmax formed in an embedded cluster with stellar mass Mecl correlates strongly with Mecl being a result of gravitation-driven but resource-limited growth and fragmentation induced starvation. There is no convincing evidence whatsoever that massive stars do form in isolation. Various methods of discretising a stellar population are introduced: optimal sampling leads to a mass distribution that perfectly represents the exact form of the desired IMF and the mmax-to-Mecl relation, while random sampling results in statistical variations of the shape of the IMF. The observed mmax-to-Mecl correlation and the small spread of IMF power-law indices together suggest that optimally sampling the IMF may be the more realistic description of star formation than random sampling from a universal IMF with a constant upper mass limit. Composite populations on galaxy scales, which are formed from many pc scale star formation events, need to be described by the integrated galactic IMF. This IGIMF varies systematically from top-light to top-heavy in dependence of galaxy type and star formation rate, with dramatic implications for theories of galaxy formation and evolution.Comment: 167 pages, 37 figures, 3 tables, published in Stellar Systems and Galactic Structure, Vol.5, Springer. This revised version is consistent with the published version and includes additional references and minor additions to the text as well as a recomputed Table 1. ISBN 978-90-481-8817-

    Ambivalence toward men: comparing sexism among Polish, South African and British university students

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    This study extends the literature on attitudes toward gender roles by exploring whether the nature of sexism (i.e., benevolence and hostility directed at men) differs among university students from two under-researched countries, Poland (n = 190) and South Africa (n = 188), in a comparison with students in the United Kingdom (n = 166). Based on empirical literature applying Ambivalent Sexism Theory, and in the light of the socio-political context, it was hypothesized that: (1) both hostile and benevolent attitudes toward men in Poland would be more liberal than in South Africa and more conservative than in the United Kingdom, and (2), women would exhibit more hostile but less benevolent attitudes than men in relatively more conservative South Africa. The Ambivalence to Men Inventory was used to measure the two types of sexist attitudes about men. Findings supported the first hypothesis for hostile attitudes and partially for benevolent attitudes. South African and Polish students were more benevolent and hostile to men than British students, and students from South Africa were more hostile than those from Poland. Moreover, as predicted, a significant country-by-gender interaction revealed that South African women had more hostile and less benevolent attitudes to men than South African men. No such gender gap was present in the case of hostile attitudes in Poland and benevolent attitudes in the United Kingdom. Findings are discussed in terms of Ambivalent Sexism Theory and the countries’ socio-cultural context

    Edging toward ‘reasonably’ good corporate governance

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    Over four decades, research and policy have created layers of understandings in the quest for “good” corporate governance. The corporate excesses of the 1970s sparked a search for market mechanisms and disclosure to empower shareholders. The UK-focused problems of the 1990s prompted board-centric, structural approaches, while the fall of Enron and many other companies in the early 2000s heightened emphasis on director independence and professionalism. With the financial crisis of 2007-09, however, came a turn in some policy approaches and in academic literature seeking a different way forward. This paper explores those four phases and the discourse each develops and then links each to assumptions about accountability and cognition. After the financial crisis came pointers n policy and practice away from narrow, rationalist prescriptions and toward what the philosopher Stephen Toulmin calls “reasonableness”. Acknowledging that heightens awareness of complexity and interdependence in corporate governance practice. The paper then articulates a research agenda concerning what “reasonable” corporate governance might entail

    Quantitative Muscle Magnetic Resonance Outcomes in Patients with Duchenne Muscular Dystrophy: An Exploratory Analysis from the EMBARK Randomized Clinical Trial

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    \ua9 2025 Vandenborne K et al. JAMA Neurology.Importance: Delandistrogene moxeparvovec is a recombinant adeno-Associated virus rhesus isolate serotype 74 vector-based gene transfer therapy for the treatment of Duchenne muscular dystrophy (DMD) in patients with a confirmed pathogenic variant of the DMD gene. In a subset of patients in the EMBARK (A Gene Transfer Therapy Study to Evaluate the Safety and Efficacy of Delandistrogene Moxeparvovec [SRP-9001] in Participants With DMD) randomized clinical trial, changes in muscle health and pathology were assessed to evaluate the therapeutic impact of the treatment on disease progression. Objective: To determine the effect of delandistrogene moxeparvovec on muscle quantitative magnetic resonance (QMR) measures of disease progression in patients in the EMBARK trial. Design, Setting, and Participants: This was a phase 3, double-blind, placebo-controlled (October 2021-September 2023; week 52 cutoff date: September 13, 2023), multicenter randomized clinical trial that included 131 patients. Patients were randomized, and 125 were treated with either delandistrogene moxeparvovec (n = 63) or placebo (n = 62). The current study focused on a subset of patients who underwent muscle QMR imaging. Intervention: Single-Administration intravenous delandistrogene moxeparvovec (1.33 7 1014 vector genome/kg) or placebo. Main Outcomes and Measures: Change from baseline to week 52 in muscle MR was a prespecified exploratory end point. Proton MR spectroscopy (MRS) and 8-point Dixon MR imaging (MRI) measured muscle fat fraction (FF); multislice spin echo MRI measured transverse relaxation time (T2). MRS FF was measured in the soleus and vastus lateralis. MRI FF and T2 were measured in 5 leg muscle locations important for ambulation. A post hoc global statistical test combining all muscles and modalities assessed overall treatment effect. Results: In this exploratory EMBARK analysis, 39 male participants (delandistrogene moxeparvovec, n = 19; placebo, n = 20; mean [SD] age, 6.10 [1.04] years; mean [SD] baseline North Star Ambulatory Assessment total score, 22.99 [3.71] points) underwent muscle MRI. Treated patients showed less disease progression vs placebo on MR measures. Across muscles and modalities, magnitudes of FF change favored delandistrogene moxeparvovec; between-group differences in least-squares mean change ranged from-1.01 (95% CI,-2.79 to 0.77; soleus) to-0.71 (95% CI,-3.21 to 1.80; vastus lateralis) for MRS FF and-3.09 (95% CI,-7.62 to 1.45; vastus lateralis) to-0.44 (95% CI,-4.01 to 3.12; hamstrings) for MRI FF. T2 reductions (improvements; 4 of 5 muscles) were observed in treated patients vs increases (worsening; all muscles) in placebo patients; within-group differences in least-squares mean change ranged from-1.06 (95% CI,-2.10 to-0.02; soleus) to 0.17 (95% CI,-1.76 to 2.10; biceps femoris) in the delandistrogene moxeparvovec group and from 1.12 (95% CI, 0.08-2.16; soleus) to 2.94 (95% CI, 0.84-5.03; quadriceps) in the placebo group. The global statistical test supported treatment benefit (P =.03). Conclusions and Relevance: Results reveal that QMR outcomes consistently favored delandistrogene moxeparvovec across muscle groups, with treatment leading to decreased fat accumulation and improved T2 vs placebo over 52 weeks. Consistent with treatment effects on functional outcomes observed in the EMBARK trial, these results suggest stabilization or less progression of muscle pathology with delandistrogene moxeparvovec-adding to the totality of evidence supporting disease stabilization or slowing of disease progression with delandistrogene moxeparvovec. Trial Registration: ClinicalTrials.gov Identifier: NCT05096221

    Fast mode decomposition in few-mode fibers

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    Retrieval of the optical phase information from measurement of intensity is of a high interest because this would facilitate simple and cost-efficient techniques and devices. In scientific and industrial applications that exploit multi-mode fibers, a prior knowledge of spatial mode structure of the fiber, in principle, makes it possible to recover phases using measured intensity distribution. However, current mode decomposition algorithms based on the analysis of the intensity distribution at the output of a few-mode fiber, such as optimization methods or neural networks, still have high computational costs and high latency that is a serious impediment for applications, such as telecommunications. Speed of signal processing is one of the key challenges in this approach. We present a high-performance mode decomposition algorithm with a processing time of tens of microseconds. The proposed mathematical algorithm that does not use any machine learning techniques, is several orders of magnitude faster than the state-of-the-art deep-learning-based methods. We anticipate that our results can stimulate further research on algorithms beyond popular machine learning methods and they can lead to the development of low-cost phase retrieval receivers for various applications of few-mode fibers ranging from imaging to telecommunications

    Streaming histogram sketching for rapid microbiome analytics

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    Background: The growth in publically available microbiome data in recent years has yielded an invaluable resource for genomic research, allowing for the design of new studies, augmentation of novel datasets and reanalysis of published works. This vast amount of microbiome data, as well as the widespread proliferation of microbiome research and the looming era of clinical metagenomics, means there is an urgent need to develop analytics that can process huge amounts of data in a short amount of time. To address this need, we propose a new method for the compact representation of microbiome sequencing data using similarity-preserving sketches of streaming k-mer spectra. These sketches allow for dissimilarity estimation, rapid microbiome catalogue searching and classification of microbiome samples in near real time. Results: We apply streaming histogram sketching to microbiome samples as a form of dimensionality reduction, creating a compressed ‘histosketch’ that can efficiently represent microbiome k-mer spectra. Using public microbiome datasets, we show that histosketches can be clustered by sample type using the pairwise Jaccard similarity estimation, consequently allowing for rapid microbiome similarity searches via a locality sensitive hashing indexing scheme. Furthermore, we use a ‘real life’ example to show that histosketches can train machine learning classifiers to accurately label microbiome samples. Specifically, using a collection of 108 novel microbiome samples from a cohort of premature neonates, we trained and tested a random forest classifier that could accurately predict whether the neonate had received antibiotic treatment (97% accuracy, 96% precision) and could subsequently be used to classify microbiome data streams in less than 3 s. Conclusions: Our method offers a new approach to rapidly process microbiome data streams, allowing samples to be rapidly clustered, indexed and classified. We also provide our implementation, Histosketching Using Little K-mers (HULK), which can histosketch a typical 2 GB microbiome in 50 s on a standard laptop using four cores, with the sketch occupying 3000 bytes of disk space
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