2,594 research outputs found
Structural parameters for globular clusters in NGC 5128. III. ACS surface-brightness profiles and model fits
We present internal surface-brightness profiles, based on HST/ACS imaging in
the F606W bandpass, for 131 globular cluster (GC) candidates with luminosities
10^4 - 3 x 10^6 solar, in the giant elliptical galaxy NGC 5128. Several
structural models are fit to the profile of each cluster and combined with
mass-to-light ratios from population-synthesis models, to derive a catalogue of
fundamental structural and dynamical parameters parallel in form to the
catalogues recently produced by McLaughlin & van der Marel and Barmby et al.
for GCs and massive young star clusters in Local Group galaxies. As part of
this, we provide corrected and extended parameter estimates for another 18
clusters in NGC 5128, which we observed previously. We show that, like GCs in
the Milky Way and some of its satellites, the majority of globulars in NGC 5128
are well fit by isotropic Wilson models, which have intrinsically more
distended envelope structures than the standard King lowered isothermal
spheres. We use our models to predict internal velocity dispersions for every
cluster in our sample. These predictions agree well in general with the
observed dispersions in a small number of clusters for which spectroscopic data
are available. In a subsequent paper, we use these results to investigate
scaling relations for GCs in NGC 5128.Comment: MNRAS, in press. 28 pages. Full data tables available at
http://www.astro.keele.ac.uk/~dem/clusters.htm
Assessment of Kinematics and Electromyography Following Arthroscopic Single-Tendon Rotator Cuff Repair
Background The increasing demand for rotator cuff (RC) repair patients to return to work as soon as they are physically able has led to exploration of when this is feasible. Current guidelines from our orthopedic surgery clinic recommend a return to work at 9 weeks postoperation. To more fully define capacity to return to work, the current study was conducted using a unique series of quantitative tools. To date, no study has combined 3-dimensional (3D) motion analysis with electromyography (EMG) assessment during activities of daily living (ADLs), including desk tasks, and commonly prescribed rehabilitation exercise. Objective To apply a quantitative, validated upper extremity model to assess the kinematics and muscle activity of the shoulder following repair of the supraspinatus RC tendon compared to that in healthy shoulders. Design A prospective, cross-sectional comparison study. Setting All participants were evaluated during a single session at the Medical College of Wisconsin Department of Orthopaedic Surgery\u27s Motion Analysis Laboratory. Participants Ten participants who were 9-12 weeks post–operative repair of a supraspinatus RC tendon tear and 10 participants with healthy shoulders (HS) were evaluated. Methods All participants were evaluated with 3D motion analysis using a validated upper extremity model and synchronized EMG. Data from the 2 groups were compared using multivariate Hotelling T2 tests with post hoc analyses based on Welch t-tests. Main Outcome Measurements Participants\u27 thoracic and thoracohumeral joint kinematics, temporal-spatial parameters, and RC muscle activity were measured by applying a quantitative upper extremity model during 10 activities of daily living and 3 rehabilitation exercises. These included tasks of hair combing, drinking, writing, computer mouse use, typing, calling, reaching to back pocket, pushing a door open, pulling a door closed, external rotation, internal rotation, and rowing. Results There were significant differences of the thoracohumeral joint motion in only a few of the tested tasks: comb maximal flexion angle (P = .004), pull door internal/external rotation range of motion (P = .020), reach abduction/adduction range of motion (P = .001), reach flexion/extension range of motion (P = .001), reach extension minimal angle (P = .025), active external rotation maximal angle (P = .012), and active external rotation minimal angle (P = .004). The thorax showed significantly different kinematics of maximal flexion angle during the call (P = .011), mouse (P = .007), and drink tasks (P = .005) between the 2 groups. The EMG data analysis showed significantly increased subscapularis activity in the RC repair group during active external rotation. Conclusions Although limited abduction was expected due to repair of the supraspinatus tendon, only a single ADL (reaching to back pocket) had a significantly reduced abduction range of motion. Thoracic motion was shown to be used as a compensatory strategy during seated ADLs. Less flexion of the thorax may create passive shoulder flexion at the thoracohumeral joint in efforts to avoid active flexion. The RC repair group participants were able to accomplish the ADLs within the same time frame and through thoracohumeral joint kinematics similar to those in the healthy shoulder group participants. In summary, this study presents a quantification of the effects of RC repair and rehabilitation on the ability to perform ADLs. It may also point to a need for increased rehabilitation focus on either regaining external rotation strength or range of motion following RC repair to enhance recovery and return to the workforce
Structural Parameters for Globular Clusters in NGC 5128. II: HST/ACS Imaging and New Clusters
We report the first results from an imaging program with the ACS camera on
HST designed to measure the structural characteristics of a wide range of
globular clusters in NGC 5128, the nearest giant elliptical galaxy. From 12
ACS/WFC fields, we have measured a total of 62 previously known globular
clusters and have discovered 69 new high-probability cluster candidates not
found in any previous work. We present magnitudes and color indices for all of
these, along with rough measurements of their effective diameters and
ellipticities. The luminosity distribution of this nearly-uncontaminated sample
of clusters matches well with the normal GCLF for giant elliptical galaxies,
and the cluster scale size and ellipticity distributions are similar to those
in the Milky Way system. The indication from this survey is that many hundreds
of individual clusters remain to be found with carefully designed search
techniques in the future. A very rough estimate of the total cluster population
from our data suggests N_GC = 1500 in NGC 5128, over all magnitudes and within
a projected radius R = 25' from the galaxy center.Comment: AASTex, 33 preprint pages including 9 Figures. Accepted for
publication in Astronomical Journal, volume 132 (2006
p66Shc activation promotes increased oxidative phosphorylation and renders CNS cells more vulnerable to amyloid beta toxicity
A key pathological feature of Alzheimer’s disease (AD) is the accumulation of the neurotoxic amyloid beta (Aβ) peptide within the brains of affected individuals. Previous studies have shown that neuronal cells selected for resistance to Aβ toxicity display a metabolic shift from mitochondrial-dependent oxidative phosphorylation (OXPHOS) to aerobic glycolysis to meet their energy needs. The Src homology/collagen (Shc) adaptor protein p66Shc is a key regulator of mitochondrial function, ROS production and aging. Moreover, increased expression and activation of p66Shc promotes a shift in the cellular metabolic state from aerobic glycolysis to OXPHOS in cancer cells. Here we evaluated the hypothesis that activation of p66Shc in CNS cells promotes both increased OXPHOS and enhanced sensitivity to Aβ toxicity. The effect of altered p66Shc expression on metabolic activity was assessed in rodent HT22 and B12 cell lines of neuronal and glial origin respectively. Overexpression of p66Shc repressed glycolytic enzyme expression and increased both mitochondrial electron transport chain activity and ROS levels in HT22 cells. The opposite effect was observed when endogenous p66Shc expression was knocked down in B12 cells. Moreover, p66Shc activation in both cell lines increased their sensitivity to Aβ toxicity. Our findings indicate that expression and activation of p66Shc renders CNS cells more sensitive to Aβ toxicity by promoting mitochondrial OXPHOS and ROS production while repressing aerobic glycolysis. Thus, p66Shc may represent a potential therapeutically relevant target for the treatment of AD
M87, Globular Clusters, and Galactic Winds: Issues in Giant Galaxy Formation
New VRI photometry is presented for the globular clusters in the innermost
140'' of the M87 halo. The results are used to discuss several issues
concerning the formation and evolution of globular cluster systems in
supergiant ellipticals like M87. (1) we find no significant change in the
globular cluster luminosity function (GCLF) with galactocentric radius, for
cluster masses M < 10^5 solar masses, indicating that the main effects of
dynamical evolution may be only on lower-mass clusters. (2) Within the core
radius (1') of the globular cluster system, the metallicity distribution is
uniform, but at larger radii the mean metallicity declines steadily as Z ~
r^-0.9. (3) The various options for explaining the existence of high specific
frequency galaxies like M87 are evaluated, and scaling laws for the GCSs in
these galaxies are given. Interpretations involving secondary evolution
(formation of many globular clusters during mergers, intergalactic globular
clusters, etc.) are unlikely to be the primary explanation for high-S_N
galaxies. (4) We suggest that central-supergiant E galaxies may have formed in
an exceptionally turbulent or high-density environment in which an early,
powerful galactic wind drove out a high fraction of the protogalactic gas, thus
artificially boosting the specificComment: 67 pages, 17 figures. To appear in Astronomical Journal, in press for
May 1998. Preprints also available from W.Harris; send e-mail request to
[email protected]
INTEGRAL deep observations of the Small Magellanic Cloud
Deep observations of the Small Magellanic Cloud (SMC) and region were carried
out in the hard X-ray band by the INTEGRAL observatory in 2008-2009. The field
of view of the instrument permitted simultaneous coverage of the entire SMC and
the eastern end of the Magellanic Bridge. In total, INTEGRAL detected seven
sources in the SMC and five in the Magellanic Bridge; the majority of the
sources were previously unknown systems. Several of the new sources were
detected undergoing bright X- ray outbursts and all the sources exhibited
transient behaviour except the supergiant system SMC X-1. They are all thought
to be High Mass X-ray Binary (HMXB) systems in which the compact object is a
neutron star.Comment: 7 pages, 10 figures Accepted for publication in MNRA
Discovery of a Probable CH Star in the Globular Cluster M14 and Implications for the Evolution of Binaries in Clusters
We report the discovery of a probable CH star in the core of the Galactic
globular cluster M14, identified from an integrated-light spectrum of the
cluster obtained with the MOS spectrograph on the CFHT. From a high- resolution
echelle spectrum of the same star obtained with the Hydra fiber positioner and
bench spectrograph on the WIYN telescope, we measure a radial velocity of
km s. Although this velocity is inconsistent with
published estimates of the systemic radial velocity of M14 (eg, km s), we use high-precision Hydra velocities for 20 stars
in the central 2.6 arcminutes of M14 to calculate improved values for the
cluster mean velocity and one-dimensional velocity dispersion: km
s and km s, respectively. Both the star's location
near the tip of the red giant branch in the cluster color magnitude diagram and
its radial velocity therefore argue for membership in M14. Since the
intermediate-resolution MOS spectrum shows not only enhanced CH absorption but
also strong Swan bands of C, M14 joins Omega Cen as the only globular
clusters known to contain classical CH stars. Although evidence for its
duplicity must await additional radial velocity measurements, the CH star in
M14 is probably, like all field CH stars, a spectroscopic binary with a
degenerate (white dwarf) secondary. The candidate and confirmed CH stars in M14
and Omega Cen, and in a number of Galactic dSph galaxies, may then owe their
existence to the long timescales for the shrinking and coalescence of hard
binaries in low-concentration environments.Comment: Accepted to the Astrophysical Journal Letters. 13 pages, AAS LaTeX
and three postscript figures (numbers 2,3,4). Entire paper (including Figure
1) available at http://www.hia.nrc.ca/DAO/SCIENCE/science.htm
The 2015 Middle Childhood Survey (MCS) of mental health and well-being at age 11 years in an Australian population cohort
Purpose: The Middle Childhood Survey (MCS) was designed as a computerised self-report assessment of children's mental health and well-being at approximately 11 years of age, conducted with a population cohort of 87 026 children being studied longitudinally within the New South Wales (NSW) Child Development Study. Participants: School Principals provided written consent for teachers to administer the MCS in class to year 6 students at 829 NSW schools (35.0% of eligible schools). Parent or child opt-outs from participation were received for 4.3% of children, and MCS data obtained from 27 808 children (mean age 11.5 years, SD 0.5; 49.5% female), representing 85.9% of students at participating schools. Findings to date: Demographic characteristics of participating schools and children are representative of the NSW population. Children completed items measuring Social Integration, Prosocial Behaviour, Peer Relationship Problems, Supportive Relationships (at Home, School and in the Community), Empathy, Emotional Symptoms, Conduct Problems, Aggression, Attention, Inhibitory Control, Hyperactivity-Inattention, Total Difficulties (internalising and externalising psychopathology), Perceptual Sensitivity, Psychotic-Like Experiences, Personality, Self-esteem, Daytime Sleepiness and Connection to Nature. Distributions of responses on each item and construct demarcate competencies and vulnerabilities within the population: most children report mental health and well-being, but the population distribution spanned the full range of possible scores on every construct. Future plans: Multiagency, intergenerational linkage of the MCS data with health, education, child protection, justice and early childhood development records took place late in 2016. Linked data were used to elucidate patterns of risk and protection across early and middle child development, and these data will provide a foundation for future record linkages in the cohort that will track mental and physical health, social and educational/occupational outcomes into adolescence and early adulthood.Kristin R Laurens, Stacy Tzoumakis, Kimberlie Dean, Sally A Brinkman, Miles Bore, Rhoshel K Lenroot, Maxwell Smith, Allyson Holbrook, Kim M Robinson, Robert Stevens, Felicity Harris, Vaughan J Carr, Melissa J Gree
New South Wales Child Development Study (NSW-CDS): an Australian multiagency, multigenerational, longitudinal record linkage study
Purpose: The initial aim of this multiagency, multigenerational record linkage study is to identify childhood profiles of developmental vulnerability and resilience, and to identify the determinants of these profiles. The eventual aim is to identify risk and protective factors for later childhood-onset and adolescent-onset mental health problems, and other adverse social outcomes, using subsequent waves of record linkage. The research will assist in informing the development of public policy and intervention guidelines to help prevent or mitigate adverse long-term health and social outcomes. Participants: The study comprises a population cohort of 87,026 children in the Australian State of New South Wales (NSW). The cohort was defined by entry into the first year of full-time schooling in NSW in 2009, at which time class teachers completed the Australian Early Development Census (AEDC) on each child (with 99.7% coverage in NSW). The AEDC data have been linked to the children's birth, health, school and child protection records for the period from birth to school entry, and to the health and criminal records of their parents, as well as mortality databases. Findings to date: Descriptive data summarising sex, geographic and socioeconomic distributions, and linkage rates for the various administrative databases are presented. Child data are summarised, and the mental health and criminal records data of the children's parents are provided. Future plans: In 2015, at age 11 years, a self-report mental health survey was administered to the cohort in collaboration with government, independent and Catholic primary school sectors. A second record linkage, spanning birth to age 11 years, will be undertaken to link this survey data with the aforementioned administrative databases. This will enable a further identification of putative risk and protective factors for adverse mental health and other outcomes in adolescence, which can then be tested in subsequent record linkages.Vaughan J Carr, Felicity Harris, Alessandra Raudino, Luming Luo, Maina Kariuki, Enwu Liu, Stacy Tzoumakis, Maxwell Smith, Allyson Holbrook, Miles Bore, Sally Brinkman, Rhoshel Lenroot, Katherine Dix, Kimberlie Dean, Kristin R Laurens, Melissa J Gree
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