2,739 research outputs found
Finite-size effects in amorphous Fe90Zr10/Al75Zr25 multilayers
The thickness dependence of the magnetic properties of amorphous Fe90Zr10
layers has been explored using Fe90Zr10/Al75Zr25 multilayers. The Al75Zr25
layer thickness is kept at 40 \AA, while the thickness of the Fe90Zr10 layers
is varied between 5 and 20 \AA. The thickness of the Al75Zr25 layers is
sufficiently large to suppress any significant interlayer coupling. Both the
Curie temperature and the spontaneous magnetization decrease non-linearly with
decreasing thickness of the Fe90Zr10 layers. No ferromagnetic order is observed
in the multilayer with 5 {\AA} Fe90Zr10 layers. The variation of the Curie
temperature with the Fe90Zr10 layer thickness is fitted with a
finite-size scaling formula [1-\Tc(t)/\Tc(\infty)]=[(t-t')/t_0]^{-\lambda},
yielding , and a critical thickness \AA, below which the
Curie temperature is zero.Comment: 8 pages, 8 figure
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Visual Analytics for Understanding Spatial Situations from Episodic Movement Data
Continuing advances in modern data acquisition techniques result in rapidly growing amounts of geo-referenced data about moving objects and in emergence of new data types. We define episodic movement data as a new complex data type to be considered in the research fields relevant to data analysis. In episodic movement data, position measurements may be separated by large time gaps, in which the positions of the moving objects are unknown and cannot be reliably reconstructed. Many of the existing methods for movement analysis are designed for data with fine temporal resolution and cannot be applied to discontinuous trajectories. We present an approach utilizing Visual Analytics methods to explore and understand the temporal variation of spatial situations derived from episodic movement data by means of spatio-temporal aggregation. The situations are defined in terms of the presence of moving objects in different places and in terms of flows (collective movements) among the places. The approach, which combines interactive visual displays with clustering of the spatial situations, is presented by example of a real dataset collected by Bluetooth sensors
Low-energy neutron-deuteron reactions with N3LO chiral forces
We solve three-nucleon Faddeev equations with nucleon-nucleon and
three-nucleon forces derived consistently in the framework of chiral
perturbation theory at next-to-next-to-next-to-leading order in the chiral
expansion. In this first investigation we include only matrix elements of the
three-nucleon force for partial waves with the total two-nucleon
(three-nucleon) angular momenta up to 3 (5/2). Low-energy neutron-deuteron
elastic scattering and deuteron breakup reaction are studied. Emphasis is put
on Ay puzzle in elastic scattering and cross sections in symmetric-space-star
and neutron-neutron quasi-free-scattering breakup configurations, for which
large discrepancies between data and theory have been reported.Comment: 22 pages, 7 figure
Few-nucleon systems with state-of-the-art chiral nucleon-nucleon forces
We apply improved nucleon-nucleon potentials up to fifth order in chiral
effective field theory, along with a new analysis of the theoretical truncation
errors, to study nucleon-deuteron (Nd) scattering and selected low-energy
observables in 3H, 4He, and 6Li. Calculations beyond second order differ from
experiment well outside the range of quantified uncertainties, providing truly
unambiguous evidence for missing three-nucleon forces within the employed
framework. The sizes of the required three-nucleon force contributions agree
well with expectations based on Weinberg's power counting. We identify the
energy range in elastic Nd scattering best suited to study three-nucleon force
effects and estimate the achievable accuracy of theoretical predictions for
various observables.Comment: 5 pages, 5 figure
Neutral pion photoproduction off 3H and 3He in chiral perturbation theory
We calculate electromagnetic neutral pion production off three-nucleon bound
states (3H, 3He) at threshold to leading one-loop order in the framework of
chiral nuclear effective field theory. In addition, we analyze the dependence
of the nuclear S-wave amplitude E_{0+} on the elementary neutron amplitude
E_{0+}^{pi0 n} which in the case of 3He provides a stringent test of the
prediction based on chiral perturbation theory. Uncertainties from higher order
corrections are estimated.Comment: 6 pages, 3 figures, version accepted for publication in Phys. Lett.
B, improved discussion of higher-order corrections, results unchange
Thermal Conversion of Guanylurea Dicyanamide into Graphitic Carbon Nitride via Prototype CNx Precursors
Guanylurea dicyanamide, [(H2N)C(-O)NHC(NH2)2][N(CN)2], has been synthesized by ion exchange reaction in aqueous solution and structurally characterized by single-crystal X-ray diffraction (C2/c, a = 2249.0(5) pm, b = 483.9(1) pm, c = 1382.4(3) pm, β = 99.49(3)°, V = 1483.8(5) × 106 pm3, T = 130 K). The thermal behavior of the molecular salt has been studied by thermal analysis, temperature-programmed X-ray powder diffraction, FTIR spectroscopy, and mass spectrometry between room temperature and 823 K. The results were interpreted on a molecular level in terms of a sequence of thermally induced addition, cyclization, and elimination reactions. As a consequence, melamine (2,4,6-triamino-1,3,5-triazine) is formed with concomitant loss of HNCO. Further condensation of melamine yields the prototypic CNx precursor melem (2,6,10-triamino-s-heptazine, C6N7(NH2)3), which alongside varying amounts of directly formed CNxHy material transforms into layered CNxHy phases without significant integration of oxygen into the core framework owing to the evaporation of HNCO. Thus, further evidence can be added to melamine and its condensation product melem acting as “key intermediates” in the synthetic pathway toward graphitic CNxHy materials, whose exact constitution is still a point at issue. Due to the characteristic formation process and hydrogen content a close relationship with the polymer melon is evident. In particular, the thermal transformation of guanylurea dicyanamide clearly demonstrates that the formation of volatile compounds such as HNCO during thermal decomposition may render a large variety of previously not considered molecular compounds suitable CNx precursors despite the presence of oxygen in the starting material
Seston quality drives feeding, stoichiometry and excretion of zebra mussels
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136507/1/fwb12892.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136507/2/fwb12892_am.pd
Threshold neutral pion photoproduction off the tri-nucleon to O(q^4)
We calculate electromagnetic neutral pion production off tri-nucleon bound
states (3H, 3He) at threshold in chiral nuclear effective field theory to
fourth order in the standard heavy baryon counting. We show that the fourth
order two-nucleon corrections to the S-wave multipoles at threshold are very
small. This implies that a precise measurement of the S-wave cross section for
neutral pion production off 3He allows for a stringent test of the chiral
perturbation theory prediction for the S-wave electric multipole E_{0+}^{pi0
n}.Comment: 17 pages, 5 figures, title changed, final version to appear in EPJA.
arXiv admin note: substantial text overlap with arXiv:1103.340
ATLAS Detector Paper Back-Up Note: Electrons and Photons
This is the supporting note to the ATLAS Detector paper for electron and photon reconstruction with the Inner Detector. It describes the software used to produce the results presented in the ATLAS Detector paper
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