5,238 research outputs found
Extending the Globular Cluster System-Halo Mass Relation to the Lowest Galaxy Masses
High mass galaxies, with halo masses , reveal
a remarkable near-linear relation between their globular cluster (GC) system
mass and their host galaxy halo mass. Extending this relation to the mass range
of dwarf galaxies has been problematic due to the difficulty in measuring
independent halo masses. Here we derive new halo masses based on stellar and HI
gas kinematics for a sample of nearby dwarf galaxies with GC systems. We find
that the GC system mass--halo mass relation for galaxies populated by GCs holds
from halo masses of down to below
, although there is a substantial increase in scatter
towards low masses. In particular, three well-studied ultra diffuse galaxies,
with dwarf-like stellar masses, reveal a wide range in their GC-to-halo mass
ratios. We compare our GC system--halo mass relation to the recent model of El
Badry et al., finding that their fiducial model does not reproduce our data in
the low mass regime. This may suggest that GC formation needs to be more
efficient than assumed in their model, or it may be due to the onset of
stochastic GC occupation in low mass halos. Finally, we briefly discuss the
stellar mass-halo mass relation for our low mass galaxies with GCs, and we
suggest some nearby dwarf galaxies for which searches for GCs may be fruitful.Comment: 16 pages, 5 figures, accepted for publication in MNRA
Taking the Quantum Eraser to the Abstract World
Youngs double slit experiment is one of the most celebrated achievements in quantum and classical optics; it provides experimental proof of the wave-particle duality of light. When the paths of the double slit are marked with orthogonal polarizations, the path information is revealed and no interference pattern is observed. However, the path information can be erased with a complimentary analysis of the polarization. Here we use hybrid entanglement between photons carrying orbital angular momentum and polarization to show that, just as in Young's experiment, the paths (OAM) marked with polarization do not lead to interference. However, when introducing the eraser (polarizer) which projects the polarization of one of the entangled photons onto a complementary polarization basis, the OAM (paths) are allowed to interfere, leading to the formation of azimuthal fringes whose frequency is proportional to the OAM content carried by the photon
Age Estimates for Galaxies in Groups
We discuss recent developments on the age and metallicity distribution for
early type galaxies in different environments.Comment: 4 pages, Latex, 2 figures, submitted to IAU 17
Zero Temperature Thermodynamics of Asymmetric Fermi Gases at Unitarity
The equation of state of a dilute two-component asymmetric Fermi gas at
unitarity is subject to strong constraints, which affect the spatial density
profiles in atomic traps. These constraints require the existence of at least
one non-trivial partially polarized (asymmetric) phase. We determine the
relation between the structure of the spatial density profiles and the T=0
equation of state, based on the most accurate theoretical predictions
available. We also show how the equation of state can be determined from
experimental observations.Comment: 10 pages and 7 figures. (Minor changes to correspond with published
version.
The case for the development and use of "ecologically valid" measures of executive function in experimental and clinical neuropsychology
This article considers the scientific process whereby new and better clinical tests of executive function might be developed, and what form they might take. We argue that many of the traditional tests of executive function most commonly in use (e.g., the Wisconsin Card Sorting Test; Stroop) are adaptations of procedures that emerged almost coincidentally from conceptual and experimental frameworks far removed from those currently in favour, and that the prolongation of their use has been encouraged by a sustained period of concentration on “construct-driven” experimentation in neuropsychology. This resulted from the special theoretical demands made by the field of executive function, but was not a necessary consequence, and may not even have been a useful one. Whilst useful, these tests may not therefore be optimal for their purpose. We consider as an alternative approach a function-led development programme which in principle could yield tasks better suited to the concerns of the clinician because of the transparency afforded by increased “representativeness” and “generalisability.” We further argue that the requirement of such a programme to represent the interaction between the individual and situational context might also provide useful constraints for purely experimental investigations. We provide an example of such a programme with reference to the Multiple Errands and Six Element tests
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Knowledge, attitudes and practices of medical staff towards obesity management in patients with spinal cord injuries: an International survey of four western European countries
Objective: To (1) examine the opinions of medical staff working in spinal cord injury (SCI) centres (SCICs); (2) evaluate their knowledge, attitudes and practices towards obesity prevention and management; (3) report the number of beds and dietitians available at each SCIC. Methods: A 37-item questionnaire was sent to 23 SCICs in the UK, the Netherlands, Belgium and the Republic of Ireland between September 2012 and January 2013. Results: Eighteen SCICs returned the questionnaires for analysis. All respondents stated that they had an interest in obesity treatment but only 2.3% of the respondents received training in obesity management. Sixty-one percent of staff did not consider body mass index (BMI) to be appropriate for use in SCI patients and subsequently less than half of the respondents use BMI routinely. The majority of respondents reported that they are confident in dealing with overweight (74.5%) and obese (66.1%) SCI adults, less than half (44.1%) are confident in treating overweight and obese SCI children. Respondents also indicated the need for nationally adopted guidelines and a lack of physical activity provision. There were 17.5 whole-time equivalent (WTE) dietitians recorded in 22 SCICs, equivalent to 47.8 beds per WTE dietitians (range 10–420). Non-UK SCIC dietitians are significantly better resourced than in UK SCICs (beds per WTE dietitian: 36 vs 124, P=0.035). Conclusion: Medical staff expressed the need to participate in obesity prevention and management. Appropriate training should be considered for all medical staff and the development of specific weight management guidelines and dietetic provision should be considered
Optical properties of high quality Cu2ZnSnSe4 thin films
Cu2ZnSnSe4 thin films, fabricated on bare or molybdenum coated glass substrates by magnetron sputtering and selenisation, were studied by a range of techniques. Photoluminescence spectra reveal an excitonic peak and two phonon replicas of a donor-acceptor pair (DAP) recombination. Its acceptor and donor ionisation energies are 27 and 7 meV, respectively. This demonstrates that high-quality Cu2ZnSnSe4 thin films can be fabricated. An experimental value for the longitudinal optical phonon energy of 28 meV was estimated. The band gap energy of 1.01 eV at room temperature was determined using optical absorption spectr
Anastrozole-Induced Carpal Tunnel Syndrome: Results From the International Breast Cancer Intervention Study II Prevention Trial
Supported in part by Cancer Research UK
(C569/A5032) and the National Health and
Medical Research Council Australia
(GNT300755, GNT569213), and in part by
AstraZeneca, who also provided
anastrozole and matching placebo. This
study was sponsored by Queen Mary
University of London, London, United
Kingdom
Participant-Reported Symptoms and Their Effect on Long-Term Adherence in the International Breast Cancer Intervention Study I (IBIS I)
Purpose: To assess the role of participant-reported symptoms on long-term adherence to preventive therapy in the United Kingdom sample of the International Breast Cancer Intervention Study (IBIS-I). IBIS-I was a randomized controlled trial that investigated the effectiveness of tamoxifen in reducing the risk of breast cancer among women at increased risk of the disease. Participants and Methods: Women were randomly assigned to tamoxifen versus placebo (20 mg/day; n = 4,279). After 456 exclusions, 3,823 women were included in this analysis. Adherence (< 4.5 years or ≥ 4.5 years) was calculated using data from six monthly clinical visits. Analyses were adjusted for age, Tyrer-Cuzick risk, smoking, use of hormone replacement therapy, menopausal status, baseline menopausal symptoms, and treatment.
Results: Overall, 69.7% of women were adherent for at least 4.5 years (tamoxifen: 65.2% v placebo: 74.0%; P .05). In both treatment arms, we observed significant trends for lower adherence with increasing severity for all symptoms (P < .01) except headaches (P = .054).
Conclusion: In the IBIS-I trial, experiencing predefined symptoms in the first 6 months reduced long-term adherence. Effects were similar between treatment arms, suggesting that women were attributing age-related symptoms to preventive therapy. Interventions were required to support symptom management
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