7,243 research outputs found
Structure and electronic properties of the () SnAu/Au(111) surface alloy
We have investigated the atomic and electronic structure of the
() SnAu/Au(111) surface alloy. Low
energy electron diffraction and scanning tunneling microscopy measurements show
that the native herringbone reconstruction of bare Au(111) surface remains
intact after formation of a long range ordered () SnAu2/Au(111) surface alloy. Angle-resolved
photoemission and two-photon photoemission spectroscopy techniques reveal
Rashba-type spin-split bands in the occupied valence band with comparable
momentum space splitting as observed for the Au(111) surface state, but with a
hole-like parabolic dispersion. Our experimental findings are compared with
density functional theory (DFT) calculation that fully support our experimental
findings. Taking advantage of the good agreement between our DFT calculations
and the experimental results, we are able to extract that the occupied Sn-Au
hybrid band is of (s, d)-orbital character while the unoccupied Sn-Au hybrid
bands are of (p, d)-orbital character. Hence, we can conclude that the
Rashba-type spin splitting of the hole-like Sn-Au hybrid surface state is
caused by the significant mixing of Au d- to Sn s-states in conjunction with
the strong atomic spin-orbit coupling of Au, i.e., of the substrate.Comment: Copyright:
https://journals.aps.org/authors/transfer-of-copyright-agreement; All
copyrights by AP
RANS-based Aerodynamic Shape Optimization of a Blended-Wing-Body Aircraft
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106453/1/AIAA2013-2586.pd
Designing and Optimizing a Healthcare Kiosk for the Community
Investigating new ways to deliver care, such as the use of self-service kiosks to collect and monitor signs of wellness, supports healthcare efficiency and inclusivity. Self-service kiosks offer this potential, but there is a need for solutions to meet acceptable standards, e.g., provision of accurate measurements. This study investigates the design and optimization of a prototype healthcare kiosk to collect vital signs measures. The design problem was decomposed, formalized, focused and used to generate multiple solutions. Systematic implementation and evaluation allowed for the optimization of measurement accuracy, first for individuals and then for a population. The optimized solution was tested independently to check the suitability of the methods, and quality of the solution. The process resulted in a reduction of measurement noise and an optimal fit, in terms of the positioning of measurement devices. This guaranteed the accuracy of the solution and provides a general methodology for similar design problems
Accuracy of Molecular Simulation-Based Predictions of koff Values: A Metadynamics Study
The koff values of ligands unbinding to proteins are key parameters for drug discovery. Their predictions based on molecular simulation may under- or overestimate experiment in a system- and/or technique-dependent way. Here we use an established method-infrequent metadynamics, based on the AMBER force field-to compute the koff of the ligand iperoxo (in clinical use) targeting the muscarinic receptor M2. The ligand charges are calculated by either (i) the Amber standard procedure or (ii) B3LYP-DFT. The calculations using (i) turn out not to provide a reasonable estimation of the transition-state free energy. Those using (ii) differ from experiment by 2 orders of magnitude. On the basis of B3LYP DFT QM/MM simulations, we suggest that the observed discrepancy in (ii) arises, at least in part, from the lack of electronic polarization and/or charge transfer in biomolecular force fields. These issues might be present in other systems, such as DNA-protein complexes
Daphnia magna modifies its gene expression extensively in response to caloric restriction revealing a novel effect on haemoglobin isoform preference
Caloric restriction (CR) produces clear phenotypic effects within and between generations of the model crustacean Daphnia magna . We have previously established that micro RNAs and cytosine methylation change in response to CR in this organism, and we demonstrate here that CR has a dramatic effect on gene expression. Over 6000 genes were differentially expressed between CR and well‐fed D. magna , with a bias towards up‐regulation of genes under caloric restriction. We identified a highly expressed haemoglobin gene that responds to CR by changing isoform proportions. Specifically, a transcript containing three haem‐binding erythrocruorin domains was strongly down‐regulated under CR in favour of transcripts containing fewer or no such domains. This change in the haemoglobin mix is similar to the response to hypoxia in Daphnia, which is mediated through the transcription factor hypoxia‐inducible factor 1, and ultimately the mTOR signalling pathway. This is the first report of a role for haemoglobin in the response to CR. We also observed high absolute expression of super‐oxide dismutase (SOD) in normally‐fed individuals, which contrasts with observations of high SOD levels under CR in other taxa. However, key differentially expressed genes, like SOD, were not targeted by differentially expressed micro‐RNAs. Whether the link between Haemoglobin and CR occurs in other organisms, or is related to the aquatic lifestyle, remains to be tested. It suggests that one response to CR may be to simply transport less oxygen and lower respiration
Super-Eddington Accretion as a Possible Scenario to Form GW190425
On 2019 April 25, the LIGO/Virgo Scientific Collaboration detected a compact
binary coalescence, GW190425. Under the assumption of the binary neutron star
(BNS), the total mass of lies five standard
deviations away from the known Galactic population mean. In the standard common
envelope scenario, the immediate progenitor of GW190425 is a close binary
system composed of an NS and a He-rich star. With the detailed binary
evolutionary modeling, we find that in order to reproduce GW190425-like events,
super-Eddington accretion (e.g., ) from a He-rich
star onto the first-born NS with a typical mass of 1.33 via stable
Case BB mass transfer (MT) is necessarily required. Furthermore, the immediate
progenitors should potentially have an initial mass of in a
range of and an initial orbital period of
from 0.08 days to 0.12 days, respectively. The corresponding mass accreted onto
NSs via stable Case BB MT phase varies from to . After the formation of the second-born NS, the BNSs are expected to
be merged due to gravitational wave emission from 11 Myr to 190
Myr.Comment: 8 pages, 10 figures, updated to add one referenc
Grain boundary effects on magnetotransport in bi-epitaxial films of LaSrMnO
The low field magnetotransport of LaSrMnO (LSMO) films
grown on SrTiO substrates has been investigated. A high qualtity LSMO film
exhibits anisotropic magnetoresistance (AMR) and a peak in the
magnetoresistance close to the Curie temperature of LSMO. Bi-epitaxial films
prepared using a seed layer of MgO and a buffer layer of CeO display a
resistance dominated by grain boundaries. One film was prepared with seed and
buffer layers intact, while a second sample was prepared as a 2D square array
of grain boundaries. These films exhibit i) a low temperature tail in the low
field magnetoresistance; ii) a magnetoconductance with a constant high field
slope; and iii) a comparably large AMR effect. A model based on a two-step
tunneling process, including spin-flip tunneling, is discussed and shown to be
consistent with the experimental findings of the bi-epitaxial films.Comment: REVTeX style; 14 pages, 9 figures. Figure 1 included in jpeg format
(zdf1.jpg); the eps was huge. Accepted to Phys. Rev.
Screening and bioinformatics analysis of a potential ceRNA network in melatonin-induced cashmere growth in Liaoning cashmere goats
The purpose of this study was to investigate the effect of melatonin (MT) on the expression patterns of lncRNA, mRNA and miRNA in Liaoning cashmere goat (LCG) skin fibroblasts. A quantity of 200 ng L−1 MT (MT group) stimulated LCG skin fibroblasts for 48 h, and RNA sequencing was conducted with the control group (Con group) (n=3). The ceRNA network was constructed by bioinformatics analysis of the sequencing data and transmission electron microscopy observation of coated pits and endocytic vesicles. In this study, the results indicated that MT treatment significantly facilitated the proliferation of LCG skin fibroblasts and increased the number of coated pits and vesicles. A total of 775 mRNAs, 57 lncRNAs and 10 miRNAs had differential expression, as indicated by RNA sequencing of skin fibroblasts administrated on the MT group and Con group. The regulatory network of ceRNA was studied, and the results suggested that inositol phosphate metabolism, the cGMP–PKG signaling pathway, endocytosis and other pathways played a certain role in the growth and development of the LCG cashmere. Moreover, the key genes (e.g., CREB1, PIK3C3, AGAP3, MEF2A, ASAP2, IRAG1, PNISR, PIP5K1A, SRSF11, ZRANB2, RBM39 and CBL) were regulated by chi-miR-34c-5p, chi-miR-34c-3p and chi-miR-195-5p. The above mRNAs were competitively bound by 15 lncRNAs (e.g., MSTRG.28630.12, MSTRG.28660.14, MSTRG.28099.7). And through dual luciferase and other experiments, it was further confirmed that PIP5K1A is the target gene of miR-34c-5p. This finding provides new insights into the molecular mechanism by which melatonin promotes villi growth in cashmere.</p
- …