68 research outputs found
Response of "Glacier-Runoff" system in a typical monsoonal temperate glacier region, Hailuogou Basin in Mt. Gongga of China, to global warming
International audienceThe method of correlation analysis and trend analysis were used in this research in order to confirm the response of "glacier-runoff" system to global warming. Hailuogou glacier had retreated by 1871.8 m over the past 76 years, Hailuogou No. 2 glacier had also retreated by 1100 m. Glaciers retreats are contrary to the climatic warming trend in China and the Northern Hemisphere. Glaciers in Hailuogou basin were in the loss with a fluctuating manner since 1950s, and accumulative value of mass balance is ?10 825.5 mm water equivalent with an annual mean value of ?240.6 mm. The inverse correlation is highly significant between mass balance variation and climatic fluctuation of China and the Northern Hemisphere after 1950s. Glacier ablation is intensive with a ratio of 7.86 m yr?1. A steady rise tendency toward glaciers runoff has been observed since 1980s, and the runoff rise is mainly responsible for melt water in Hailuogou basin. It is noticeable that climatic warming not only strengthened ablation extent and enlarged ablation area, but also prolonged ablation period. Global warming is the main cause of glacier retreat, mass loss and runoff rise in Hailuogou basin
Thermosensitive Cu2O-PNIPAM core-shell nanoreactors with tunable photocatalytic activity
We report a facile and novel method for the fabrication of Cu2O@PNIPAM
core-shell nanoreactors using Cu2O nanocubes as the core. The PNIPAM shell not
only effectively protects the Cu2O nanocubes from oxidation, but also improves
the colloidal stability of the system. The Cu2O@PNIPAM core-shell microgels can
work efficiently as photocatalyst for the decomposition of methyl orange under
visible light. A significant enhancement in the catalytic activity has been
observed for the core-shell microgels compared with the pure Cu2O nanocubes.
Most importantly, the photocatalytic activity of the Cu2O nanocubes can be
further tuned by the thermosensitive PNIPAM shell, as rationalized by our
recent theory.Comment: 8 pages, 6 figures (Supporting Information included: 11 pages, 10
figures
Semi-quantitative analysis of geological samples using laser plasma time-of-flight mass spectrometry
A method has been developed that allows the direct measurement of the elemental composition of geological samples based on a newly developed laser plasma time-of-flight mass spectrometer with a collisional cooling system. This technique has the merits of small sample consumption and rapid elemental analysis. Four geological reference materials were used in the experiment. The system has shown a satisfactory resolving power with few interferences in the spectra. The limits of detection were about 10(-6)-10(-7) g g(-1) for most of the metal elements. The relative sensitivity coefficients (RSCs) of the elements with mass heavier than 30 amu could be used for direct semi-quantitative analysis.National 863 program ; Fujian Province Department of Science Technology ; National Natural Science Foundation of Chin
Sciences for The 2.5-meter Wide Field Survey Telescope (WFST)
The Wide Field Survey Telescope (WFST) is a dedicated photometric survey
facility under construction jointly by the University of Science and Technology
of China and Purple Mountain Observatory. It is equipped with a primary mirror
of 2.5m in diameter, an active optical system, and a mosaic CCD camera of 0.73
Gpix on the main focus plane to achieve high-quality imaging over a field of
view of 6.5 square degrees. The installation of WFST in the Lenghu observing
site is planned to happen in the summer of 2023, and the operation is scheduled
to commence within three months afterward. WFST will scan the northern sky in
four optical bands (u, g, r, and i) at cadences from hourly/daily to
semi-weekly in the deep high-cadence survey (DHS) and the wide field survey
(WFS) programs, respectively. WFS reaches a depth of 22.27, 23.32, 22.84, and
22.31 in AB magnitudes in a nominal 30-second exposure in the four bands during
a photometric night, respectively, enabling us to search tremendous amount of
transients in the low-z universe and systematically investigate the variability
of Galactic and extragalactic objects. Intranight 90s exposures as deep as 23
and 24 mag in u and g bands via DHS provide a unique opportunity to facilitate
explorations of energetic transients in demand for high sensitivity, including
the electromagnetic counterparts of gravitational-wave events detected by the
second/third-generation GW detectors, supernovae within a few hours of their
explosions, tidal disruption events and luminous fast optical transients even
beyond a redshift of 1. Meanwhile, the final 6-year co-added images,
anticipated to reach g about 25.5 mag in WFS or even deeper by 1.5 mag in DHS,
will be of significant value to general Galactic and extragalactic sciences.
The highly uniform legacy surveys of WFST will also serve as an indispensable
complement to those of LSST which monitors the southern sky.Comment: 46 pages, submitted to SCMP
ULK1/2 Constitute a Bifurcate Node Controlling Glucose Metabolic Fluxes in Addition to Autophagy
揭示了在外界能量供应缺乏时,细胞通过激活ULK1来介导葡萄糖分解代谢重编程以维持胞内的能量与氧化还原稳态的详细机制,并创新地发现了ULK1独立于自噬的关键功能。基于自噬和糖代谢与人类健康的重要相关性,该研究将很可能为我们预防和治疗各类代谢疾病提供新的思路和药物靶点。Metabolic reprogramming is fundamental to biological homeostasis, enabling cells to adjust metabolic routes after sensing altered availability of fuels and growth factors. ULK1 and ULK2 represent key integrators that relay metabolic stress signals to the autophagy machinery. Here, we demonstrate that, during deprivation of amino acid and growth factors, ULK1/2 directly phosphorylate key glycolytic enzymes including hexokinase (HK), phosphofructokinase 1 (PFK1), enolase 1 (ENO1), and the gluconeogenic enzyme fructose-1,6-bisphosphatase (FBP1). Phosphorylation of these enzymes leads to enhanced HK activity to sustain glucose uptake but reduced activity of FBP1 to block the gluconeogenic route and reduced activity of PFK1 and ENO1 to moderate drop of glucose-6-phosphate and to repartition more carbon flux to pentose phosphate pathway (PPP), maintaining cellular energy and redox homeostasis at cellular and organismal levels. These results identify ULK1/2 as a bifurcate-signaling node that sustains glucose metabolic fluxes besides initiation of autophagy in response to nutritional deprivation.State Key Program of National Natural Science of China, the 973 Program;National Natural Science Foundation of China for Fostering Talents in Basic Research ;the Foundation for Innovative Research Groups of the National Natural Science Foundation of China; and the 111 Project of Education of China
Hierarchical Support Vector Machines for Audio Classification *
Abstract. Audio data is one of typical multimedia data and it contains plenty of information. Audio retrieval is becoming important content in multimedia information retrieval. In multimedia retrieval researches, it becomes more and more important research part how to construct better classifiers for audio classification and retrieval. Support Vector Machines, a novel method of the Pattern Recognition, presents excellent performance in solving the problems with small sample, nonlinear and local minima. But audio classification is a multi-class classification problem and it’s just one of problems to be solved in SVM researches. In this paper, it compares several common Support Vector Machines and proposes a hierarchical Support Vector Machines based on audio features cluster method, combining audio features and hierarchical SVMS. It uses hierarchical classification method to classify audio data and it’s proved better performance by experiments
Retrieval of Sports Video Clips Using Audio-Visual Features and Text Information *
Abstract. Video clip retrieval plays a critical role in the content-based sports video retrieval. This paper proposes a content-based retrieval strategy of sports video clip in which visual and auditory features and text information are extracted to locate similar video clips. Because in sports game play scenes are concerned and interested for most audiences, a long sport video is first automatically segmented into play segments and time-out segments based on audio feature in compressed domain. And then we obtain similar video clips based on sliding shot window algorithm and equivalence relation theory. Finally similar video clips are ranked by visual factor and order factor in terms of longest common sequence (LCS). The experimental results showed that the proposed method could effectively and efficiently retrieve similar video clips corresponding with a query clip in a sports video of TV program
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