548 research outputs found
Recommended from our members
Geological Mapping of the Debussy Quadrangle (H-14) Preliminary Results
Geological mapping of Mercury is crucial to build an understanding of the history of the planet and to set the context for BepiColombo’s observations [1]. Geo-logical mapping of the Debussy quadrangle (H-14) is now underway as part of a program to map the entire planet at a scale of 1:3M using MESSENGER data [2]. The quadrangle is located in the southern hemisphere of Mercury at 0o – 90o E and 22.5o – 65o S. This will be the first high resolution map of the quadrangle as it was not imaged by Mariner 10
Structure maps for hcp metals from first principles calculations
The ability to predict the existence and crystal type of ordered structures
of materials from their components is a major challenge of current materials
research. Empirical methods use experimental data to construct structure maps
and make predictions based on clustering of simple physical parameters. Their
usefulness depends on the availability of reliable data over the entire
parameter space. Recent development of high throughput methods opens the
possibility to enhance these empirical structure maps by {\it ab initio}
calculations in regions of the parameter space where the experimental evidence
is lacking or not well characterized. In this paper we construct enhanced maps
for the binary alloys of hcp metals, where the experimental data leaves large
regions of poorly characterized systems believed to be phase-separating. In
these enhanced maps, the clusters of non-compound forming systems are much
smaller than indicated by the empirical results alone.Comment: 7 pages, 4 figures, 1 tabl
Posting selfies and body image in young adult women: The selfie paradox
This exploratory study was designed to investigate how young women make sense of their decision to post selfies, and perceived links between selfie posting and body image. Eighteen 19-22 year old British women were interviewed about their experiences of taking and posting selfies, and interviews were analysed using inductive thematic analysis. Women linked selfie posting to the ‘ideal’ body, identity management, and body exposure; objectifying their own and others’ selfies, and trying to portray an image that was as close to ‘ideal’ as possible. Women differentiated between their ‘unreal’, digitally manipulated online selfie identity and their ‘real’ identity outside Facebook and Instagram. Bodies were expected to be covered, and sexualised selfies were to be avoided. Results challenge conceptualisations of women as empowered and self-determined selfie posters; although women sought to control their image online, posting was constrained by postfeminist notions of what was considered socially appropriate to post
An Integrated Geologic Map of the Rembrandt Basin, on Mercury, as a Starting Point for Stratigraphic Analysis
Planetary geologic maps are usually carried out following a morpho-stratigraphic approach where morphology is the dominant character guiding the remote sensing image interpretation. On the other hand, on Earth a more comprehensive stratigraphic approach is preferred, using lithology, overlapping relationship, genetic source, and ages as the main discriminants among the different geologic units. In this work we produced two different geologic maps of the Rembrandt basin of Mercury, following the morpho-stratigraphic methods and symbology adopted by many authors while mapping quadrangles on Mercury, and an integrated geo-stratigraphic approach, where geologic units were distinguished also on the basis of their false colors (derived by multispectral image data of the NASA MESSENGER mission), subsurface stratigraphic position (inferred by crater excavation) and model ages. We distinguished two different resurfacing events within the Rembrandt basin, after the impact event, and four other smooth plains units outside the basin itself. This provided the basis to estimate thicknesses, volumes, and ages of the smooth plains inside the basin. Results from thickness estimates obtained using different methodologies confirm the presence of two distinct volcanic events inside the Rembrandt basin, with a total thickness ranging between 1−1.5 km. Furthermore, model ages suggest that the volcanic infilling of the Rembrandt basin is among the ones that extended well into the mid-Calorian period, when Mercury’s effusive volcanism was previously thought to be largely over
Live imaging of alveologenesis in precision-cut lung slices reveals dynamic epithelial cell behaviour
Damage to alveoli, the gas-exchanging region of the lungs, is a component of many chronic and acute lung diseases. In addition, insufficient generation of alveoli results in bronchopulmonary dysplasia, a disease of prematurity. Therefore visualising the process of alveolar development (alveologenesis) is critical for our understanding of lung homeostasis and for the development of treatments to repair and regenerate lung tissue. Using long-term, time-lapse imaging of precision-cut lung slices, we show alveologenesis for the first time. We reveal that during this process, epithelial cells are highly mobile and we identify specific cell behaviours that contribute to alveologenesis: cell clustering, hollowing and cell extension. Using the cytoskeleton inhibitors blebbistatin and cytochalasin D, we showed that cell migration is a key driver of alveologenesis. This study reveals important novel information about lung biology and provides a new system in which to manipulate alveologenesis genetically and pharmacologically
Thermodynamic properties of binary HCP solution phases from special quasirandom structures
Three different special quasirandom structures (SQS) of the substitutional
hcp binary random solutions (, 0.5, and 0.75) are
presented. These structures are able to mimic the most important pair and
multi-site correlation functions corresponding to perfectly random hcp
solutions at those compositions. Due to the relatively small size of the
generated structures, they can be used to calculate the properties of random
hcp alloys via first-principles methods. The structures are relaxed in order to
find their lowest energy configurations at each composition. In some cases, it
was found that full relaxation resulted in complete loss of their parental
symmetry as hcp so geometry optimizations in which no local relaxations are
allowed were also performed. In general, the first-principles results for the
seven binary systems (Cd-Mg, Mg-Zr, Al-Mg, Mo-Ru, Hf-Ti, Hf-Zr, and Ti-Zr) show
good agreement with both formation enthalpy and lattice parameters measurements
from experiments. It is concluded that the SQS's presented in this work can be
widely used to study the behavior of random hcp solutions.Comment: 15 pages, 8 figure
An empirical test for cellular automaton models of traffic flow
Based on a detailed microscopic test scenario motivated by recent empirical
studies of single-vehicle data, several cellular automaton models for traffic
flow are compared. We find three levels of agreement with the empirical data:
1) models that do not reproduce even qualitatively the most important empirical
observations,
2) models that are on a macroscopic level in reasonable agreement with the
empirics, and 3) models that reproduce the empirical data on a microscopic
level as well.
Our results are not only relevant for applications, but also shed new light
on the relevant interactions in traffic flow.Comment: 28 pages, 36 figures, accepted for publication in PR
Asymmetric magnetic anomalies over young impact craters on Mercury
Mercury's crustal magnetic field map includes anomalies that are related to impact craters. Mercury's surface has a low iron abundance, but it is likely that some impactors brought magnetic carriers able to register the planet's magnetic field that was present during impact. Anomalies associated with the relatively young Rustaveli and Stieglitz craters are asymmetric with respect to the crater center. We analyze the location of the magnetic anomalies and the impact crater morphologies to understand whether there is any correlation. We investigate the geological framework of these two craters to constrain the overall impact dynamics. In both cases, magnetic anomalies correlate well with the location of impact melt and the inferred impact direction. Both impact angles were probably 40–45°, with preferential distribution of the melt downrange. Inversion dipoles suggest that the impact melt located downrange encompasses some magnetized material, which is hence likely responsible for the detected magnetic anomalies
The Structure of Barium in the hcp Phase Under High Pressure
Recent experimental results on two hcp phases of barium under high pressure
show interesting variation of the lattice parameters. They are here interpreted
in terms of electronic structure calculation by using the LMTO method and
generalized pseudopotential theory (GPT) with a NFE-TBB approach. In phase II
the dramatic drop in c/a is an instability analogous to that in the group II
metals but with the transfer of s to d electrons playing a crucial role in Ba.
Meanwhile in phase V, the instability decrease a lot due to the core repulsion
at very high pressure. PACS numbers: 62.50+p, 61.66Bi, 71.15.Ap, 71.15Hx,
71.15LaComment: 29 pages, 8 figure
- …