Steinhardtite is a new mineral from the Khatyrka meteorite; it is a new allotropic form of aluminum. It occurs as rare crystals up to approximately 10 µm across in meteoritic fragments that contain ...evidence of a heterogeneous distribution of pressures and temperatures during impact shock, in which some portions of the meteorite reached at least 5 GPa and 1200 °C. The meteorite fragments contain the high-pressure phases ahrensite, coesite, stishovite, and an unnamed spinelloid with composition Fe3-xSixO4 (x ≈ 0.4). Other minerals include trevorite, Ni-Al-Mg-Fe spinels, magnetite, diopside, forsterite, clinoenstatite, nepheline, pentlandite, Cu-bearing troilite, icosahedrite, khatyrkite, cupalite, taenite, and Al-bearing taenite. Given the exceedingly small grain size of steinhardtite, it was not possible to determine most of the physical properties for the mineral. A mean of 9 electron microprobe analyses (obtained from two different fragments) gave the formula Al0.38Ni0.32Fe0.30, on the basis of 1 atom. A combined TEM and single-crystal X-ray diffraction study revealed steinhardtite to be cubic, space group Im3m, with a = 3.0214(8) Å, and V = 27.58(2) Å3, Z = 2. In the crystal structure R1 = 0.0254, the three elements are disordered at the origin of the unit cell in a body-centered-cubic packing (α-Fe structure type). The five strongest powder-diffraction lines d in Å (I/I0) (hkl) are: 2.1355 (100) (110); 1.5100 (15) (200); 1.2329 (25) (211); 0.9550 (10) (310); 0.8071 (30) (321). The new mineral has been approved by the IMA-NMNC Commission (2014-036) and named in honor of Paul J. Steinhardt, Professor at the Department of Physics of Princeton University, for his extraordinary and enthusiastic dedication to the study of the mineralogy of the Khatyrka meteorite, a unique CV3 carbonaceous chondrite containing the first natural quasicrystalline phase icosahedrite. The recovery of the polymorph of Al described here that contains essential amounts of Ni and Fe suggests that Al could be a contributing candidate for the anomalously low density of the Earth"s presumed Fe-Ni core.
We discuss the panchromatic properties of 99 088 galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 1 'main' spectroscopic sample (a flux-limited sample for 1360 deg2). These ...galaxies are positionally matched to sources detected by ROSAT, Galaxy Evolution Explorer (GALEX), two-Micron All-Sky Survey (2MASS), Infrared Astronomical Satellite (IRAS), Green Bank GB6 survey (GB6), Faint Images of the Radio Sky at Twenty-centimetres (FIRST), NRAO VLA Sky Survey (NVSS) and Westerbork Northern Sky Survey (WENSS). The matching fraction varies from <1 per cent for ROSAT and GB6 to ∼40 per cent for GALEX and 2MASS. In addition to its size, the advantages of this sample are well-controlled selection effects, faint flux limits and the wealth of measured parameters, including accurate X-ray to radio photometry, angular sizes and optical spectra. We find strong correlations between the detection fraction at other wavelengths and optical properties such as flux, colours and emission-line strengths. For example, ∼2/3 of SDSS 'main' galaxies classified as active galactic nucleus (AGN) using emission-line strengths are detected by 2MASS, while the corresponding fraction for star-forming galaxies (SFs) is only ∼1/10. Similarly, over 90 per cent of galaxies detected by IRAS display strong emission lines in their optical spectra, compared to ∼50 per cent for the whole SDSS sample. Using GALEX, SDSS and 2MASS data, we construct the ultraviolet-infrared (UV-IR) broad-band spectral energy distributions for various types of galaxies, and find that they form a nearly one-parameter family. For example, the SDSS u- and r-band data, supplemented with redshift, can be used to 'predict'K-band magnitudes measured by 2MASS with an rms scatter of only 0.2 mag. When a dust content estimate determined from SDSS spectra with the aid of models is also utilized, this scatter decreases to 0.1 mag and can be fully accounted for by measurement uncertainties. We demonstrate that this interstellar dust content, inferred from optical SDSS spectra by Kauffmann et al., is indeed higher for galaxies detected by IRAS and that it can be used to 'predict' measured IRAS 60 μm flux density within a factor of 2 using only SDSS data. We also show that the position of a galaxy in the emission-line-based Baldwin-Phillips-Terlevich diagram is correlated with the optical light concentration index and u−r colour determined from the SDSS broad-band imaging data, and discuss changes in the morphology of this diagram induced by requiring detections at other wavelengths. Notably, we find that SDSS 'main' galaxies detected by GALEX include a non-negligible fraction (10-30 per cent) of AGNs, and hence do not represent a clean sample of starburst galaxies. We study the IR-radio correlation and find evidence that its slope may be different for AGN and SFs and related to the Hα/Hβ line-strength ratio.
Abstract
LF-
µ
SR studies have previously been used to study the diffusive 1D motion of solitons and polarons in conducting polymers. This type of study was also applied to investigating the ...diffusive motion of spinons in spin-1/2 antiferromagnetic chains. Recently the method has been extended to examples of 2D layered triangular spin lattices which can support quantum spin liquid states, such as 1T-TaS
2
and YbZnGaO
4
. These systems are found to show spin dynamics that matches well to 2D spin diffusion, such a model being found to provide a much better fit to the data than previously proposed models for spin correlations in such systems. In YbZnGaO
4
the diffusion rate shows a clear crossover between classical and quantum regimes as
T
falls below the exchange coupling
J
. That the spin diffusion approach works well in the high
T
classical region might be expected, but it is found that it also works equally well in the low
T
quantum region where quantum entanglement controls the spin dynamics. Measurement of the diffusion rate allows a
T
dependent length scale to be derived from the data that can be assigned to a quantum entanglement length
ξ
E
. Another entanglement measure, the Quantum Fisher Information
F
Q
can also be obtained from the data and its
T
dependence is compared to that of
ξ
E
.
We report the observation of a two-dimensional (2D) checkerboard charge density wave (CDW) in the low-dimensional superconductor Ta4Pd3Te16. By determining its CDW properties across the ...temperature-pressure (T-P) phase diagram and comparing with prototypical CDW materials, we conclude that Ta4Pd3Te16 features: a) an incommensurate CDW with a mixed character of dimensions (Q1D considering its needle-like shape along the b-axis, Q2D as the CDW has checkerboard wavevectors, and 3D because of CDW projections along all three axes); and b) one of the weakest CDWs compared to its superconductivity (SC), i.e. enhanced SC with respect to CDW, suggesting an interesting interplay of the two orders.
MnP is a metal that shows successive magnetic transitions from paramagnetic to ferromagnetic and helical magnetic phases at ambient pressure with decreasing temperature. With applied pressure, the ...magnetic transition temperatures decrease and superconductivity appears around 8 GPa where the magnetic order is fully suppressed and the quantum critical behavior is observed. These results suggest that MnP is an unconventional superconductor in which magnetic fluctuations may be relevant to the superconducting pairing mechanism. In order to elucidate the magnetic ground state adjacent to the superconducting phase first discovered in Mn-based materials, high-pressure neutron diffraction measurements have been performed in hydrostatic pressure up to 7.5 GPa. The helical magnetic structure with the propagation vector along the \(b\) axis, reported previously at 3.8 GPa, was found to be robust up to 7.5 GPa. First principles and classical Monte Carlo calculations have also been performed to understand how the pressure-driven magnetic phase transitions are coupled with change of the exchange interactions. The calculations, which qualitatively reproduce the magnetic structures as a function of pressure, suggest that the exchange interactions change drastically with applied pressure and the further-neighbor interactions become more influential at high pressures. Combining the experimental and theoretical results, we describe the detail of exchange interactions in the vicinity of the superconducting phase which is critical to understand the pairing mechanism of the unconventional superconductivity in MnP.
In the early twentieth century, Chinese traditional architecture and the French-derived methods of the École des Beaux-Arts converged in the United States when Chinese students were given ...scholarships to train as architects at American universities whose design curricula were dominated by Beaux-Arts methods. Upon their return home in the 1920s and 1930s, these graduates began to practice architecture and create China's first architectural schools, often transferring a version of what they had learned in the U.S. to Chinese situations. The resulting complex series of design-related transplantations had major implications for China between 1911 and 1949, as it simultaneously underwent cataclysmic social, economic, and political changes. After 1949 and the founding of the People's Republic, China experienced a radically different wave of influence from the Beaux-Arts through advisors from the Soviet Union who, first under Stalin and later Khrushchev, brought Beaux-Arts ideals in the guise of socialist progress. In the early twenty-first century, China is still feeling the effects of these events.Chinese Architecture and the Beaux-Artsexamines the coalescing of the two major architectural systems, placing significant shifts in architectural theory and practice in China within relevant, contemporary, cultural, and educational contexts. Fifteen major scholars from around the world analyze and synthesize these crucial events to shed light on the dramatic architectural and urban changes occurring in China today-many of which have global ramifications.This stimulating and generously illustrated work is divided into three sections, framed by an introduction and a postscript. The first focuses on the convergence of Chinese architecture and the École des Beaux-Arts, outlining the salient aspects of each and suggesting how and why the two "met" in the U.S. The second section centers on the question of how Chinese architects were influenced by the Beaux-Arts and how Chinese architecture was changed as a result. The third takes an even closer look at the Beaux-Arts influence, addressing how innovative practices, new schools of architecture, and buildings whose designs were linked to Beaux-Arts assumptions led to distinctive new paradigms that were rooted in a changing China. By virtue of its scope, scale, and scholarship, this volume promises to become a classic in the fields of Chinese and Western architectural history.
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