16,704 research outputs found

    Influence of Potamogeton crispus growth on nutrients in the sediment and water of Lake Tangxunhu

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    An incubation experiment was performed on Potamogeton crispus (P. crispus) using sediment collected from Lake Tangxunhu in the center of China, in order to determine the effects of plant growth on Fe, Si, Cu, Zn, Mn, Mg, P, and Ca concentrations in the sediments and overlying waters. After 3 months of incubation, Ca, Mg, and Si concentrations in the water column were significantly lower, and P and Cu concentrations were significantly higher than in unplanted controls. The effect of P. crispus growth on sediment pore waters and water-extractable elements varied. Concentrations of Ca, Mg, Si, Fe, Cu, and Zn were significantly higher, and P was significantly lower, than in pore waters of the control. Water-extracted concentrations of Fe, Mg, and Si in the sediments were lower, and P was higher, than in the control. Presence of P. crispus generally enhanced concentration gradients of elements between pore waters and overlying waters but not for P. The growth of P. crispus was associated with an increase in water pH and formation of root plaques, resulting in complex effects on the sediment nutritional status

    Microscopic correlation between chemical and electronic states in epitaxial graphene on SiC(000-1)

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    We present energy filtered electron emission spectromicroscopy with spatial and wave-vector resolution on few layer epitaxial graphene on SiC$(000-1) grown by furnace annealing. Low energy electron microscopy shows that more than 80% of the sample is covered by 2-3 graphene layers. C1s spectromicroscopy provides an independent measurement of the graphene thickness distribution map. The work function, measured by photoelectron emission microscopy (PEEM), varies across the surface from 4.34 to 4.50eV according to both the graphene thickness and the graphene-SiC interface chemical state. At least two SiC surface chemical states (i.e., two different SiC surface structures) are present at the graphene/SiC interface. Charge transfer occurs at each graphene/SiC interface. K-space PEEM gives 3D maps of the k_|| pi - pi* band dispersion in micron scale regions show that the Dirac point shifts as a function of graphene thickness. Novel Bragg diffraction of the Dirac cones via the superlattice formed by the commensurately rotated graphene sheets is observed. The experiments underline the importance of lateral and spectroscopic resolution on the scale of future electronic devices in order to precisely characterize the transport properties and band alignments

    Spectroscopic ellipsometry and electrical studies of as-grown and rapid thermal oxidized Si\u3csub\u3e1−x−y\u3c/sub\u3eGe\u3csub\u3ex\u3c/sub\u3eC\u3csub\u3ey\u3c/sub\u3e films

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    Transmission electron microscopy results showed the formation of SiC precipitation in a rapid thermally oxidized (RTO) Si1−x−yGexCy sample with high-C content. The spectroscopic ellipsometry results showed that the E1 gap increased and E2 gap decreased as the C concentration increased. For the oxidized samples, the amplitude of the E2 transitions reduced rapidly and the E1 transition shifted to a lower energy. The reduction in the E2 transitions was due to the presence of the oxide layer. A high-Ge content layer and the low-C content in the RTO films accounted for the E1 shift to lower energy. The electrical measurements showed that RTO at 800 °C did not improve the oxide quality as compared to 1000 °C

    Electrical Properties of Rapid Thermal Oxides on Si\u3csub\u3e1−x−y\u3c/sub\u3eGe\u3csub\u3ex\u3c/sub\u3eC\u3csub\u3ey\u3c/sub\u3e Films

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    The electrical characteristics of rapid thermal oxides on Si1−x−yGexCy layers are reported. X-ray photoelectron spectroscopy results indicate segregation of Ge at the SiO2/Si1−x−yGexCy interface, a thin GeO2 layer at the oxide surface, and elemental Ge at the interface and in the oxide. The interface state density of the samples ranges from 3.0×1011 to 3.6×1012 eV−1 cm−2. All the samples show electron trapping behavior and the trap generation rate decreases with increasing C concentration. The charge-to-breakdown value and the oxide breakdown field are higher for Si0.887Ge0.113 than for Si1−x−yGexCy samples, and these values decrease with increasing C concentration

    Molecular cloning and characterization of the germline-restricted chromosome sequence in the zebra finch

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    The zebra finch (Taeniopygia guttata) germline-restricted chromosome (GRC) is the largest chromosome and has a unique system of transmission in germ cells. In the male, the GRC exists as a single heterochromatic chromosome in the germline and is eliminated from nuclei in late spermatogenesis. In the female, the GRC is bivalent and euchromatic and experiences recombination. These characteristics suggest a female-specific or female-beneficial function of the GRC. To shed light on the function of GRC, we cloned a portion of the GRC using random amplified polymorphic DNA–polymerase chain reaction and analyzed it using molecular genetic and cytogenetic methods. The GRC clone hybridized strongly to testis but not blood DNA in genomic Southern blots. In fluorescent in situ hybridization analysis on meiotic chromosomes from synaptonemal complex spreads, the probe showed hybridization across a large area of the GRC, suggesting that it contains repetitive sequences. We isolated a sequence homologous to the GRC from zebra finch chromosome 3 and a region of chicken chromosome 1 that is homologous to zebra finch chromosome 3; the phylogenetic analysis of these three sequences suggested that the GRC sequence and the zebra finch chromosome 3 sequence are most closely related. Thus, the GRC sequences likely originated from autosomal DNA and have evolved after the galliform–passeriform split. The present study provides a foundation for further study of the intriguing GRC

    99mTc-labelled Stealth® liposomal doxorubicin (Caelyx®) in glioblastomas and metastatic brain tumours

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    British Journal of Cancer (2002) 86, 659–660. DOI: 10.1038/sj/bjc/6600093 www.bjcancer.co

    Expressive Stream Reasoning with Laser

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    An increasing number of use cases require a timely extraction of non-trivial knowledge from semantically annotated data streams, especially on the Web and for the Internet of Things (IoT). Often, this extraction requires expressive reasoning, which is challenging to compute on large streams. We propose Laser, a new reasoner that supports a pragmatic, non-trivial fragment of the logic LARS which extends Answer Set Programming (ASP) for streams. At its core, Laser implements a novel evaluation procedure which annotates formulae to avoid the re-computation of duplicates at multiple time points. This procedure, combined with a judicious implementation of the LARS operators, is responsible for significantly better runtimes than the ones of other state-of-the-art systems like C-SPARQL and CQELS, or an implementation of LARS which runs on the ASP solver Clingo. This enables the application of expressive logic-based reasoning to large streams and opens the door to a wider range of stream reasoning use cases.Comment: 19 pages, 5 figures. Extended version of accepted paper at ISWC 201

    A fast, high voltage, high frequency modulator at BNL

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    Sensor-Assisted Global Motion Estimation for Efficient UAV Video Coding

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    This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record.In this paper, we propose a novel video coding scheme to significantly reduce the coding complexity and enhance overall coding efficiency in videos acquired by high mobility devices such as unmanned aerial vehicles (UAVs). In order to reduce the encoded data bits and encoding time to facilitate real-time data transmission, as well as minimize the image distortion caused by the jitter of onboard camera, a sensor-assisted global motion estimation (GMV) algorithm is designed to calculate perspective transformation model and global motion vectors, which are used in both the inter-frame coding to improve the coding efficiency and intra-frame coding to reduce block search complexity. We conducted comprehensive simulation experiments on official HM-16.10 codec and the performance results show the proposed method can achieve faster block search by 50% to 60% speedup and lower bitrate by 15% to 30% compared with standard HEVC coding software
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