1,653 research outputs found
Crystal structure of Cu-Sn-In alloys around the {\eta} phase field studied by neutron diffraction
The study of the Cu-Sn-In ternary system has become of great importance in
recent years, due to new environmental regulations forcing to eliminate the use
of Pb in bonding technologies for electronic devices. A key relevant issue
concerns the intermetallic phases which grow in the bonding zone and are
determining in their quality and performance. In this work, we focus in the
{\eta}-phase (Cu2In or Cu6Sn5) that exists in both end binaries and as a
ternary phase. We present a neutron diffraction study of the constitution and
crystallography of a series of alloys around the 60 at.% Cu composition, and
with In contents ranging from 0 to 25 at.%, quenched from 300\degreeC. The
alloys were characterized by scanning electron microscopy, probe microanalysis
and high-resolution neutron diffraction. The Rietveld refinement of neutron
diffraction data allowed to improve the currently available model for site
occupancies in the hexagonal {\eta}-phase in the binary Cu-Sn as well as in
ternary alloys. For the first time, structural data is reported in the ternary
Cu-Sn-In {\eta}-phase as a function of composition, information that is of
fundamental technological importance as well as valuable input data for ongoing
modelisations of the ternary phase diagram.Comment: 8 pages, 10 figure
Understorey plant community and light availability in conifer plantations and natural hardwood forests in Taiwan
Questions: What are the effects of replacing mixed species natural forests with Cryptomeria japonica plantations on understorey plant functional and species diversity? What is the role of the understorey light environment in determining understorey diversity and community in the two types of forest?
Location: Subtropical northeast Taiwan.
Methods: We examined light environments using hemispherical photography, and diversity and composition of understorey plants of a 35‐yr C. japonica plantation and an adjacent natural hardwood forest.
Results: Understorey plant species richness was similar in the two forests, but the communities were different; only 18 of the 91 recorded understorey plant species occurred in both forests. Relative abundance of plants among different functional groups differed between the two forests. Relative numbers of shade‐tolerant and shade‐intolerant seedling individuals were also different between the two forest types with only one shade‐intolerant seedling in the plantation compared to 23 seedlings belonging to two species in the natural forest. In the natural forest 11 species of tree seedling were found, while in the plantation only five were found, and the seedling density was only one third of that in the natural forest. Across plots in both forests, understorey plant richness and diversity were negatively correlated with direct sunlight but not indirect sunlight, possibly because direct light plays a more important role in understorey plant growth.
Conclusions: We report lower species and functional diversity and higher light availability in a natural hardwood forest than an adjacent 30‐yr C. japonica plantation, possibly due to the increased dominance of shade‐intolerant species associated with higher light availability. To maintain plant diversity, management efforts must be made to prevent localized losses of shade‐adapted understorey plants
Recent developments in planet migration theory
Planetary migration is the process by which a forming planet undergoes a
drift of its semi-major axis caused by the tidal interaction with its parent
protoplanetary disc. One of the key quantities to assess the migration of
embedded planets is the tidal torque between the disc and planet, which has two
components: the Lindblad torque and the corotation torque. We review the latest
results on both torque components for planets on circular orbits, with a
special emphasis on the various processes that give rise to additional, large
components of the corotation torque, and those contributing to the saturation
of this torque. These additional components of the corotation torque could help
address the shortcomings that have recently been exposed by models of planet
population syntheses. We also review recent results concerning the migration of
giant planets that carve gaps in the disc (type II migration) and the migration
of sub-giant planets that open partial gaps in massive discs (type III
migration).Comment: 52 pages, 18 figures. Review article to be published in "Tidal
effects in Astronomy and Astrophysics", Lecture Notes in Physic
How to compare arc-annotated sequences: The alignment hierarchy
International audienceWe describe a new unifying framework to express comparison of arc-annotated sequences, which we call alignment of arc-annotated sequences. We first prove that this framework encompasses main existing models, which allows us to deduce complexity results for several cases from the literature. We also show that this framework gives rise to new relevant problems that have not been studied yet. We provide a thorough analysis of these novel cases by proposing two polynomial time algorithms and an NP-completeness proof. This leads to an almost exhaustive study of alignment of arc-annotated sequences
Cosmological distance indicators
We review three distance measurement techniques beyond the local universe:
(1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and
(3) HI intensity mapping. We describe the principles and theory behind each
method, the ingredients needed for measuring such distances, the current
observational results, and future prospects. Time delays from strongly lensed
quasars currently provide constraints on with < 4% uncertainty, and with
1% within reach from ongoing surveys and efforts. Recent exciting discoveries
of strongly lensed supernovae hold great promise for time-delay cosmography.
BAO features have been detected in redshift surveys up to z <~ 0.8 with
galaxies and z ~ 2 with Ly- forest, providing precise distance
measurements and with < 2% uncertainty in flat CDM. Future BAO
surveys will probe the distance scale with percent-level precision. HI
intensity mapping has great potential to map BAO distances at z ~ 0.8 and
beyond with precisions of a few percent. The next years ahead will be exciting
as various cosmological probes reach 1% uncertainty in determining , to
assess the current tension in measurements that could indicate new
physics.Comment: Review article accepted for publication in Space Science Reviews
(Springer), 45 pages, 10 figures. Chapter of a special collection resulting
from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in
the Space Ag
Large-scale pharmacogenomic study of sulfonylureas and the QT, JT and QRS intervals: CHARGE Pharmacogenomics Working Group
Sulfonylureas, a commonly used class of medication used to treat type 2 diabetes, have been associated with an increased risk of cardiovascular disease. Their effects on QT interval duration and related electrocardiographic phenotypes are potential mechanisms for this adverse effect. In 11 ethnically diverse cohorts that included 71 857 European, African-American and Hispanic/Latino ancestry individuals with repeated measures of medication use and electrocardiogram (ECG) measurements, we conducted a pharmacogenomic genome-wide association study of sulfonylurea use and three ECG phenotypes: QT, JT and QRS intervals. In ancestry-specific meta-analyses, eight novel pharmacogenomic loci met the threshold for genome-wide significance (P<5 × 10−8), and a pharmacokinetic variant in CYP2C9 (rs1057910) that has been associated with sulfonylurea-related treatment effects and other adverse drug reactions in previous studies was replicated. Additional research is needed to replicate the novel findings and to understand their biological basis
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
This paper reports a measurement of D*+/- meson production in jets from
proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the
CERN Large Hadron Collider. The measurement is based on a data sample recorded
with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets
with transverse momentum between 25 and 70 GeV in the pseudorapidity range
|eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay
chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate
is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for
D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z <
1. Monte Carlo predictions fail to describe the data at small values of z, and
this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table,
matches published version in Physical Review
Standard Model Matrix Elements for Neutral B-Meson Mixing and Associated Decay Constants
We present results of quenched lattice calculations of the matrix elements
relevant for B_d-\bar B_d and B_s-\bar B_s mixing in the Standard Model.
Results for the corresponding SU(3)-breaking ratios, which can be used to
constrain or determine |V_{td}|, are also given. The calculations are performed
at two values of the lattice spacing, corresponding to \beta = 6.0 and \beta =
6.2, with quarks described by a mean-field-improved Sheikholeslami-Wohlert
action. As a by-product, we obtain the leptonic decay constants of B and D
mesons. We also present matrix elements relevant for D^0-\bar D^0 mixing. Our
results are summarized in the Introduction.Comment: 27 pages (RevTeX), 26 figures, version published in Phys. Rev. D:
improved estimate of the systematic error associated with the uncertainty on
the strange quark mass and other small improvements to analysis (results
change only slightly); correction of typos and minor changes to text; RevTeX
formattin
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