980 research outputs found
M/L and Color Evolution for A Deep Sample of M* Cluster Galaxies at z~1: The Formation Epoch and the Tilt of the Fundamental Plane
We have measured velocity dispersions for a sample of 36 galaxies with J <
21.2 or Mr < -20.6 mag in MS1054-03, a massive cluster of galaxies at z = 0.83.
Our data are of uniformly high quality down to our selection limit, our 16-hour
exposures typically yielding errors of only \delta(dispersion)~10% for L* and
fainter galaxies. By combining our measurements with data from the literature,
we have 53 cluster galaxies with measured dispersions, and HST/ACS-derived
sizes, colors and surface brightnesses. This sample is complete for the typical
L* galaxy at z~1, unlike most previous z~1 cluster samples which are complete
only for the massive cluster members (>1e11 M_sun). We find no evidence for a
change in the tilt of the fundamental plane (FP). Nor do we find evidence for
evolution in the slope of the color-dispersion relation and M/L_B-dispersion
relations; measuring evolution at a fixed dispersion should minimize the impact
of size evolution found in other work. The M/L_B at fixed dispersion evolves by
\Delta log10 M/L_B=-0.50 +/- 0.03 between z=0.83 and z=0.02 or d(log10
M/L_B)=-0.60 +/- 0.04 dz, and we find \Delta (U-V)_z=-0.24 +/- 0.02 mag at
fixed dispersion in the rest-frame, matching the expected evolution in M/L_B
within 2.25 standard deviations. The implied formation redshift from both the
color and M/L_B evolution is z*=2.0 +/- 0.2 +/- 0.3 (sys), during the epoch in
which the cosmic star-formation activity peaked, with the systematic
uncertainty showing the dependence of z* on the assumptions we make about the
stellar populations. The lack of evolution in either the tilt of the FP or in
the M/L- and color-dispersion relations imply that the formation epoch depends
weakly on mass, ranging from z*=2.3 +1.3 -0.3 at 300 km/s to z*=1.7 +0.3 -0.2
at 160 km/s and implies that the IMF similarly varies slowly with galaxy mass.Comment: revised; typos corrected, references updated, and other cosmetic
changes to meet ApJ format ApJ accepted, 22 pages in emulate ApJ format, 8
color figures, 1 b/w figur
Simulative Investigations of the Influence of Surface Indentations on Residual Stresses on Inner Raceways for Roller Element Bearings
Resource-efficient machine elements are in the focus of current research. One of the most widely used machine elements are roller bearings. Thus, the optimization of bearings and their tribological properties promises to result in significant resource savings. Special focus is set on the bearing fatigue life, which may be significantly reduced by indentations on the raceways. The reduction in fatigue life can be caused by processes such as rolling over particles or by brinelling. These processes induce local stress peaks and lead to elastic-plastic deformations of the raceways. During the subsequent operation, the pile up of material around the indentations is flattened and hence the residual stresses change. Inside these so called shoulders stress pealcs, residual stresses and hardening effects occur possibly resulting in crack initiation, crack growth under cyclic loading, and eventually spalling of material. For deeper and more sharp-edged indentations the bearing fatigue life is reduced more. To quantify the influence of an indentation on the bearing rating life a calculation model was developed based on the approach of IOANNIDES, BERGLING and GABELLI. For this, a 3D-FE model is used to calculate the three dimensional stress fields by superposition of residual and load stresses
Categorizing Health Outcomes and Efficacy of mHealth Apps for Persons With Cognitive Impairment: A Systematic Review
Background
Use of mobile health (mHealth) apps is growing at an exponential rate in the United States and around the world. Mild cognitive impairment (MCI), Alzheimer disease, and related dementias are a global health problem. Numerous mHealth interventions exist for this population, yet the effect of these interventions on health has not been systematically described.
Objective
The aim of this study is to catalog the types of health outcomes used to measure effectiveness of mHealth interventions and assess which mHealth interventions have been shown to improve the health of persons with MCI, Alzheimer disease, and dementia.
Methods
We searched 13 databases, including Ovid MEDLINE, PubMed, EMBASE, the full Cochrane Library, CINAHL, PsycINFO, Ei Compendex, IEEE Xplore, Applied Science & Technology Source, Scopus, Web of Science, ClinicalTrials.gov, and Google Scholar from inception through May 2017 for mHealth studies involving persons with cognitive impairment that were evaluated using at least one quantitative health outcome. Proceedings of the Annual ACM Conferences on Human Factors in Computing Systems, the ACM User Interface Software and Technology Symposium, and the IEEE International Symposium on Wearable Computers were searched in the ACM Digital Library from 2012 to 2016. A hand search of JMIR Publications journals was also completed in July 2017.
Results
After removal of duplicates, our initial search returned 3955 records. Of these articles, 24 met final inclusion criteria as studies involving mHealth interventions that measured at least one quantitative health outcome for persons with MCI, Alzheimer disease, and dementia. Common quantitative health outcomes included cognition, function, mood, and quality of life. We found that 21.2% (101/476) of the fully reviewed articles were excluded because of a lack of health outcomes. The health outcomes selected were observed to be inconsistent between studies. For those studies with quantitative health outcomes, more than half (58%) reported postintervention improvements in outcomes.
Conclusions
Results showed that many mHealth app interventions targeting those with cognitive impairment lack quantitative health outcomes as a part of their evaluation process and that there is a lack of consensus as to which outcomes to use. The majority of mHealth app interventions that incorporated health outcomes into their evaluation noted improvements in the health of persons with MCI, Alzheimer disease, and dementia. However, these studies were of low quality, leading to a grade C level of evidence. Clarification of the benefits of mHealth interventions for people with cognitive impairment requires more randomized controlled trials, larger numbers of participants, and trial designs that minimize bias.
Trial Registration
PROSPERO Registration: PROSPERO 2016:CRD42016033846; http://www.crd.york.ac.uk/PROSPERO/ display_record.asp?ID=CRD42016033846 (Archived by WebCite at http://www.webcitation.org/6sjjwnv1M
Analysis of the UK Government's 2011 tourism policy
This review considers the UK Government's 2011 tourism policy document. The policy was produced during a period of public sector restructuring in the UK and also during the global economic crisis, which began in 2008. The policy sets out a number of reforms to the governance of tourism at the national and local levels, which aim to increase the level of private sector involvement in leading and developing the tourism sector and to reduce the sector's dependence on public funding. During a period of economic slowdown in the UK, the tourism industry can make a significant contribution to growth, but it is not yet clear whether these proposed reforms will support or impede the future development of the tourism industry in the UK
The near-infrared luminosity function of cluster galaxies beyond redshift one
We determined the K band luminosity function (LF) of cluster galaxies at
redshift z~1.2, using near-infrared images of three X-ray luminous clusters at
z=1.11,1.24,1.27. The composite LF was derived down to M*+4, by means of
statistical background subtraction, and is well described by a Schechter
function with K*=20.5 AB mag and alpha=-1.
From the K band composite LF we derived the stellar mass function of cluster
galaxies. Using available X-ray mass profiles we determined the M/L ratios of
these three clusters, which tend to be lower than those measured in the local
universe.
With these data, no significant difference can be seen between the shapes of
the cluster galaxies LF and the LF of field galaxies at similar redshift.
We also found no significant evolution out to z ~1.2 in the bright (<M*+4)
part of the cluster galaxies LF probed in this study, apart from a brightening
of ~1.3 mag of the characteristic magnitude of the high redshift LF. We
confirm, and extend to higher redshift, the result from previous work that the
redshift evolution of the characteristic magnitude M* is consistent with
passive evolution of a stellar population formed at z>2.
The results obtained in this work support and extend previous findings that
most of the stars in bright galaxies were formed at high redshift, and that
K-bright (M>10^11 Msun) galaxies were already in place at z ~ 1.2, at least in
the central regions of X-ray luminous clusters. Together with recent results on
the field galaxies stellar mass function, this implies that most of the stellar
mass is already assembled in massive galaxies by z ~ 1, both in low and high
density environments.Comment: 16 pages, 10 figures, to appear in A&
Photo-antagonism of the GABAA receptor
Neurotransmitter receptor trafficking is fundamentally important for synaptic transmission and neural network activity. GABAA receptors and inhibitory synapses are vital components of brain function, yet much of our knowledge regarding receptor mobility and function at inhibitory synapses is derived indirectly from using recombinant receptors, antibody-tagged native receptors and pharmacological treatments. Here we describe the use of a set of research tools that can irreversibly bind to and affect the function of recombinant and neuronal GABAA receptors following ultraviolet photoactivation. These compounds are based on the competitive antagonist gabazine and incorporate a variety of photoactive groups. By using site-directed mutagenesis and ligand-docking studies, they reveal new areas of the GABA binding site at the interface between receptor β and α subunits. These compounds enable the selected inactivation of native GABAA receptor populations providing new insight into the function of inhibitory synapses and extrasynaptic receptors in controlling neuronal excitation
Bacterial microevolution and the Pangenome
The comparison of multiple genome sequences sampled from a bacterial population reveals considerable diversity in both the core and the accessory parts of the pangenome. This diversity can be analysed in terms of microevolutionary events that took place since the genomes shared a common ancestor, especially deletion, duplication, and recombination. We review the basic modelling ingredients used implicitly or explicitly when performing such a pangenome analysis. In particular, we describe a basic neutral phylogenetic framework of bacterial pangenome microevolution, which is not incompatible with evaluating the role of natural selection. We survey the different ways in which pangenome data is summarised in order to be included in microevolutionary models, as well as the main methodological approaches that have been proposed to reconstruct pangenome microevolutionary history
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