25,306 research outputs found
Multivariate adaptive regression splines for estimating riverine constituent concentrations
Regression-based methods are commonly used for riverine constituent concentration/flux estimation, which is essential for guiding water quality protection practices and environmental decision making. This paper developed a multivariate adaptive regression splines model for estimating riverine constituent concentrations (MARS-EC). The process, interpretability and flexibility of the MARS-EC modelling approach, was demonstrated for total nitrogen in the Patuxent River, a major river input to Chesapeake Bay. Model accuracy and uncertainty of the MARS-EC approach was further analysed using nitrate plus nitrite datasets from eight tributary rivers to Chesapeake Bay. Results showed that the MARS-EC approach integrated the advantages of both parametric and nonparametric regression methods, and model accuracy was demonstrated to be superior to the traditionally used ESTIMATOR model. MARS-EC is flexible and allows consideration of auxiliary variables; the variables and interactions can be selected automatically. MARS-EC does not constrain concentration-predictor curves to be constant but rather is able to identify shifts in these curves from mathematical expressions and visual graphics. The MARS-EC approach provides an effective and complementary tool along with existing approaches for estimating riverine constituent concentrations
KDM2B/FBXL10 targets c-Fos for ubiquitylation and degradation in response to mitogenic stimulation.
KDM2B (also known as FBXL10) controls stem cell self-renewal, somatic cell reprogramming and senescence, and tumorigenesis. KDM2B contains multiple functional domains, including a JmjC domain that catalyzes H3K36 demethylation and a CxxC zinc-finger that recognizes CpG islands and recruits the polycomb repressive complex 1. Here, we report that KDM2B, via its F-box domain, functions as a subunit of the CUL1-RING ubiquitin ligase (CRL1/SCF(KDM2B)) complex. KDM2B targets c-Fos for polyubiquitylation and regulates c-Fos protein levels. Unlike the phosphorylation of other SCF (SKP1-CUL1-F-box)/CRL1 substrates that promotes substrates binding to F-box, epidermal growth factor (EGF)-induced c-Fos S374 phosphorylation dissociates c-Fos from KDM2B and stabilizes c-Fos protein. Non-phosphorylatable and phosphomimetic mutations at S374 result in c-Fos protein which cannot be induced by EGF or accumulates constitutively and lead to decreased or increased cell proliferation, respectively. Multiple tumor-derived KDM2B mutations impaired the function of KDM2B to target c-Fos degradation and to suppress cell proliferation. These results reveal a novel function of KDM2B in the negative regulation of cell proliferation by assembling an E3 ligase to targeting c-Fos protein degradation that is antagonized by mitogenic stimulations
The Properties of H{\alpha} Emission-Line Galaxies at z = 2.24
Using deep narrow-band and -band imaging data obtained with
CFHT/WIRCam, we identify a sample of 56 H emission-line galaxies (ELGs)
at with the 5 depths of and (AB)
over 383 arcmin area in the ECDFS. A detailed analysis is carried out
with existing multi-wavelength data in this field. Three of the 56 H
ELGs are detected in Chandra 4 Ms X-ray observation and two of them are
classified as AGNs. The rest-frame UV and optical morphologies revealed by
HST/ACS and WFC3 deep images show that nearly half of the H ELGs are
either merging systems or with a close companion, indicating that the
merging/interacting processes play a key role in regulating star formation at
cosmic epoch z=2-3; About 14% are too faint to be resolved in the rest-frame UV
morphology due to high dust extinction. We estimate dust extinction from SEDs.
We find that dust extinction is generally correlated with H luminosity
and stellar mass (SM). Our results suggest that H ELGs are
representative of star-forming galaxies (SFGs). Applying extinction correction
for individual objects, we examine the intrinsic H luminosity function
(LF) at , obtaining a best-fit Schechter function characterized by a
faint-end slope of . This is shallower than the typical slope of
in previous works based on constant extinction correction.
We demonstrate that this difference is mainly due to the different extinction
corrections. The proper extinction correction is thus key to recovering the
intrinsic LF as the extinction globally increases with H luminosity.
Moreover, we find that our H LF mirrors the SM function of SFGs at the
same cosmic epoch. This finding indeed reflects the tight correlation between
SFR and SM for the SFGs, i.e., the so-called main sequence.Comment: 15 pages, 12 figures, 2 tables, Received 2013 October 11; accepted
2014 February 13; published 2014 March 18 by Ap
Hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells
We study the hybrid exciton-polaritons in a bad microcavity containing the
organic and inorganic quantum wells. The corresponding polariton states are
given. The analytical solution and the numerical result of the stationary
spectrum for the cavity field are finishedComment: 3 pages, 1 figure. appear in Communications in Theoretical Physic
A Robust Image Watermarking Based on Image Restoration Using SIFT
This paper introduces a novel robust watermarking scheme for digital images, which is robust against common signal processing and geometric distortion attacks. In order to be resistant to geometric distortion attacks, the matched feature points determined by the scale-invariance feature transform (SIFT) are used for image restoration to reduce the synchronization errors caused by geometric distortion attacks. An adaptive embedding scheme is applied in discrete Fourier transform (DFT) domain of each subimage. The watermark detection decision is based on the number of matched bits between the retrieved and original watermark in the embedding image blocks. Experimental results show that the proposed watermarking is robust to common signal processing attacks and geometric distortion attacks, including rotation, scaling, cropping, shearing and some combined attacks
Thermal Performance Analysis of High-temperature Heat Transfer Process of Solar Energy
Volumetric solar receivers (VSR) have become a promising technology for the solar thermal conversion. The absorption of the concentrated solar radiation and the heat transfer to the working fluid are the two dominant processes. Firstly, the effects of two typical modeling approaches of the concentrated solar radiation for receiver are compared in view of porosity and mean cell size. Then, the radiation transport within the solar window and the porous absorber is fully simulated. The effects of porous structure parameters, slope error of the concentrator, and the alignment error of the receiver are analyzed.
Keywords: volumetric solar receivers (VSR), Monte Carlo ray tracing method, concentrated solar radiation, heat transfe
A review of process advancement of novel metal spinning
Metal spinning technology has seen a rapid development in recent years. Novel spinning processes, such as non-axisymmetrical spinning, non-circular cross-section spinning and tooth-shaped spinning, are being developed. This has challenged the limitation of traditional spinning technology being used for manufacturing axisymmetrical, circular cross-section, and uniform wall-thickness parts. In this paper, the classification of the traditional spinning processes is proposed based on the material deformation characteristics, the relative position between roller and blank, mandrel spinning and mandrel-free spinning, and temperature of the blank during spinning. The advancement of recently developed novel spinning processes and corresponding tool design and equipment development are reviewed. The classification of the novel spinning processes is proposed based on the relative position between the rotating axes, the geometry of cross-section and the variation of wall-thickness of the spun parts. The material deformation mechanism, processing failures and spun part defects of the aforementioned three groups of novel spinning processes are discussed by analyzing four representative spinning processes of industrial applications. Furthermore, other novel spinning processes and their classification as reported in the literature are summarized
Raman Spectroscopy Study of alpha-, beta-, gamma-NaxCoO2 and gamma-(Ca,Sr)xCoO2
Raman spectroscopy measurements have been performed on alpha-, beta-,
gamma-NaxCoO2 phases differing in their stacking of CoO6 octahedra along the
c-axis direction. The results demonstrate that, in general, there are five
active phonons for gamma-Na0.75CoO2, two Raman active phonons for alpha-NaCoO2,
and four Raman active phonons for beta-NaCoO2. We have also performed Raman
scattering measurements on several gamma-(Ca,Sr)xCoO2 (0.15 <= x <= 0.35)
samples which show well-defined intercalated Ca/Sr-ordering. The experimental
data show that the intercalated cation ordering could result in visible
alterations on Raman spectral structures. The observations of the spectral
changes along with the variation of the CoO6 stacking, as well as the
intercalated Sr/Ca ordering suggest that the interlayer interaction plays an
important role for understanding the lattice dynamics in this layered system.Comment: 23 pages, 5 figures, Physical Review B, in pres
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