5,018 research outputs found
Variations in the Upper Paleolithic Adaptations of North China: A Review of the Evidence and Implications for the Onset of Food Production
The Upper Paleolithic (UP) of North China has the richest archaeological data and longest history of research in the Paleolithic archaeology of China, but there is a relative lack of systematic studies addressing human adaptations. This paper explores the spatial and temporal variability of human adaptations in terms of mobility, the key variable in the adaptive systems of hunter-gatherers. We find that before the UP, little adaptive differentiation is shown in the archaeological record of North China. The early Upper Paleolithic (EUP) is distinguished by four distinctive modes of mobility and subsistence organized roughly along lines of habitat variation. These modes persisted in the Late Upper Paleolithic (LUP), underlying the widespread prevalence of microblade technology throughout North China. This pattern significantly influenced adaptive changes during the transition from the terminal Pleistocene to early Holocene. Earliest food production emerged in hilly flank habitats where EUP mobility decreased quickly and social organization was more complex. This retrospective view of UP adaptations highlights the important role that prior conditions played at the evolutionary crossroads of prehistoric North China
Extreme case of Faraday effect: magnetic splitting of ultrashort laser pulses in plasmas
The Faraday effect, caused by a magnetic-field-induced change in the optical
properties, takes place in a vast variety of systems from a single atomic layer
of graphenes to huge galaxies. Currently, it plays a pivot role in many
applications such as the manipulation of light and the probing of magnetic
fields and material's properties. Basically, this effect causes a polarization
rotation of light during its propagation along the magnetic field in a medium.
Here, we report an extreme case of the Faraday effect where a linearly
polarized ultrashort laser pulse splits in time into two circularly polarized
pulses of opposite handedness during its propagation in a highly magnetized
plasma. This offers a new degree of freedom for manipulating ultrashort and
ultrahigh power laser pulses. Together with technologies of ultra-strong
magnetic fields, it may pave the way for novel optical devices, such as
magnetized plasma polarizers. In addition, it may offer a powerful means to
measure strong magnetic fields in laser-produced plasmas.Comment: 18 pages, 5 figure
Evolution of negative superhumps, quasi-periodic oscillations and outbursts in the Z Cam-type dwarf nova AH Her
AH Her is a Z Cam-type dwarf nova with an orbital period of ~ 0.258 d. Dwarf
nova oscillations and long-period dwarf nova oscillations have been detected,
but no quasi-periodic oscillations (QPOs) and negative superhumps (NSHs) have
been found. We investigated the association between NSHs, QPOs, and outbursts
of AH Her based on \textit{TESS} photometry. We find for the first time the
NSHs with a period of 0.24497(1) d in AH Her, and trace the variation of the
amplitude and period of NSHs with the outburst. The amplitude of the NSHs is
most significant at quiescence, weakening as the outburst rises, becoming
undetectable at the top, rebounding and weakening at the plateau, and
strengthening again as the outburst declines. The variation of the accretion
disk radius can explain the NSHs amplitude variation except for the plateau, so
we suggest that the relationship between NSHs amplitude and outburst can be
used as a window to study the accretion disk instability and the origin of
NSHs. In addition, we find the periodic variations in the amplitude, maxima,
and shape of the NSHs ranging from 2.33(2) d to 2.68(5) d, which may be related
to the precession of the tilted disk. Finally, we find QPOs at the top of AH
Her's long outburst with ~ 2800 s similar to HS 2325+8205, suggesting that the
presence of QPOs at the top of Z Cam's long outburst may be a general
phenomenonComment: 20 pages, 11 figures, accepted for publication in the Astrophysical
Journa
SketchSampler: Sketch-based 3D Reconstruction via View-dependent Depth Sampling
Reconstructing a 3D shape based on a single sketch image is challenging due
to the large domain gap between a sparse, irregular sketch and a regular, dense
3D shape. Existing works try to employ the global feature extracted from sketch
to directly predict the 3D coordinates, but they usually suffer from losing
fine details that are not faithful to the input sketch. Through analyzing the
3D-to-2D projection process, we notice that the density map that characterizes
the distribution of 2D point clouds (i.e., the probability of points projected
at each location of the projection plane) can be used as a proxy to facilitate
the reconstruction process. To this end, we first translate a sketch via an
image translation network to a more informative 2D representation that can be
used to generate a density map. Next, a 3D point cloud is reconstructed via a
two-stage probabilistic sampling process: first recovering the 2D points (i.e.,
the x and y coordinates) by sampling the density map; and then predicting the
depth (i.e., the z coordinate) by sampling the depth values at the ray
determined by each 2D point. Extensive experiments are conducted, and both
quantitative and qualitative results show that our proposed approach
significantly outperforms other baseline methods.Comment: 16 pages, 7 figures, accepted by ECCV 202
Effects of immersing treatment of curcumin and piperine combined with vacuum packaging on the quality of salmon (Salmo salar) during cold chain logistics
In order to study the effects of the compound preservatives (curcumin and piperine (CP)) and vacuum packaging (VP) on the quality of salmon during cold chain logistics suffered from temperature abuse, the physiochemical indexes (texture, water holding capacity (WHC), total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), free amino acids (FAA) contents), microbial indicators (total mesophilic bacteria count (MBC), total psychrotrophic bacteria count (PBC), H2S-producing bacteria count (HSBC)) were determined, and the moisture changes were explored by near-infrared (NIR) spectroscopy and low-field nuclear magnetic resonance (LF-NMR). The results showed that the treatment of curcumin and piperine in combination with vacuum packaging could maintain the quality of salmon suffered from temperature abuse most effectively. At the end of storage, the MBC of VP+CP was only 4.95 log CFU/g, which was about 1 log CFU/g lower than the control sample stored at the same condition. The combined treatment also retarded the increase of TVB-N, TBARS, and the decrease of hardness, springiness, and a* value, as well as water migration in salmon, contributing to higher water holding capacity and better appearance. Besides, VP+CP retarded the decrease of free glutamate, which contributed to umami taste. Due to the biological activity and safety of the preserves, the combined treatment could be a promising method for preservation of seafood.Peer reviewe
TetraÂaquaÂtetraÂkisÂ(4,4′-bipyridine dioxide-κO)terbium(III) octaÂcyanidotungstate(V)
In the title compound, [Tb(C10H8N2O2)4(H2O)4][W(CN)8], both metal atoms are eight-coordinated. The TbIII ion displays a dodecaÂhedral geometry, while the Wv ion exhibits a distorted square-antiÂprismatic geometry. The Tb atoms are located on a special position of site symmetry -4, whereas the W atoms are located on a twofold rotation axis. The cations are linked by O—H⋯O hydrogen bonds. The title compound is isotypic with the corresponding and previously described Mo compound [Qian & Yuan (2011 â–¶). Acta Cryst. E67, m845]
3-Ethyl 5-methyl 2-hydrÂoxy-6-methyl-4-(4-nitroÂphenÂyl)-2-trifluoroÂmethyl-1,2,3,4-tetraÂhydroÂpyridine-3,5-dicarboxylÂate
In the title compound, C18H19F3N2O7, the tetrahydropyridine ring adopts a half-chair conformation. The nitro group is disordered over two sites with occupancies of 0.780 (15) and 0.220 (15). An intraÂmolecular N—H⋯F hydrogen bond is observed in the molÂecular structure. The molÂecules are linked into a two-dimensional network parallel to (100) by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds
Gap Anisotropy in Iron-Based Superconductors: A Point-Contact Andreev Reflection Study of BaFeNiAs Single Crystals
We report a systematic investigation on c-axis point-contact Andreev
reflection (PCAR) in BaFeNiAs superconducting single crystals
from underdoped to overdoped regions (0.075 ). At optimal
doping () the PCAR spectrum feature the structures of two
superconducting gap and electron-boson coupling mode. In the scenario,
quantitative analysis using a generalized Blonder-Tinkham-Klapwijk (BTK)
formalism with two gaps: one isotropic and another angle dependent, suggest a
nodeless state in strong-coupling limit with gap minima on the Fermi surfaces.
Upon crossing above the optimal doping (), the PCAR spectrum show an
in-gap sharp narrow peak at low bias, in contrast to the case of underdoped
samples (), signaling the onset of deepened gap minima or nodes in the
superconducting gap. This result provides evidence of the modulation of the gap
amplitude with doping concentration, consistent with the calculations for the
orbital dependent pair interaction mediated by the antiferromagnetic spin
fluctuations.Comment: 5 pages, 4 figure
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