194 research outputs found

    Compatibility analysis of precipitation and runoff trends over the large Siberian watersheds

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    The consistency of long-term yearly precipitation and runoff trends over the largest Arctic watersheds (Ob, Yenisei and Lena Rivers) is examined. Three gridded precipitation datasets (Climatic Research Unit, University of Delaware, NCEP) are used for comparative analyses with runoff data collected at basin outlets. The results generally demonstrate inconsistency in long-term changes of basin precipitation and runoff. The Yenisei River runoff increases significantly, while precipitation data show mostly negative trends. The Ob River does not show any significant trend either in precipitation or runoff. Positive trend in the Lena River runoff is accompanied by a weak precipitation increase; however, the precipitation increase is not strong enough to support the observed runoff change. The inconsistency identified in basin precipitation and runoff trends suggests uncertainty in both the quality of basin precipitation and runoff datasets, as well as the perceived hydrologic factors impacting runoff change

    L-functions of Symmetric Products of the Kloosterman Sheaf over Z

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    The classical nn-variable Kloosterman sums over the finite field Fp{\bf F}_p give rise to a lisse Qˉl\bar {\bf Q}_l-sheaf Kln+1{\rm Kl}_{n+1} on Gm,Fp=PFp1{0,}{\bf G}_{m, {\bf F}_p}={\bf P}^1_{{\bf F}_p}-\{0,\infty\}, which we call the Kloosterman sheaf. Let Lp(Gm,Fp,SymkKln+1,s)L_p({\bf G}_{m,{\bf F}_p}, {\rm Sym}^k{\rm Kl}_{n+1}, s) be the LL-function of the kk-fold symmetric product of Kln+1{\rm Kl}_{n+1}. We construct an explicit virtual scheme XX of finite type over SpecZ{\rm Spec} {\bf Z} such that the pp-Euler factor of the zeta function of XX coincides with Lp(Gm,Fp,SymkKln+1,s)L_p({\bf G}_{m,{\bf F}_p}, {\rm Sym}^k{\rm Kl}_{n+1}, s). We also prove similar results for kKln+1\otimes^k {\rm Kl}_{n+1} and kKln+1\bigwedge^k {\rm Kl}_{n+1}.Comment: 16 page

    On the geometry dependence of differential pathlength factor for near-infrared spectroscopy. I. Steady-state with homogeneous medium

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    This work analytically examines some dependences of the differential pathlength factor (DPF) for steady-state photon diffusion in a homogeneous medium on the shape, dimension, and absorption and reduced scattering coefficients of the medium. The medium geometries considered include a semi-infinite geometry, an infinite-length cylinder evaluated along the azimuthal direction, and a sphere. Steady-state photon fluence rate in the cylinder and sphere geometries is represented by a form involving the physical source, its image with respect to the associated extrapolated half-plane, and a radius-dependent term, leading to simplified formula for estimating the DPFs. With the source-detector distance and medium optical properties held fixed across all three geometries, and equal radii for the cylinder and sphere, the DPF is the greatest in the semi-infinite and the smallest in the sphere geometry. When compared to the results from finite-element method, the DPFs analytically estimated for 10 to 25 mm source-detector separations on a sphere of 50 mm radius with μₐ = 0.01 mm-1 and μ′ₛ=1.0 mm-1 are on average less than 5% different. The approximation for sphere, generally valid for a diameter ≥20 times of the effective attenuation pathlength, may be useful for rapid estimation of DPFs in near-infrared spectroscopy of an infant head and for short source-detector separation.Electrical & Computer Engineerin

    Daily quantification of myoglobin forms on beef longissimus lumborum steaks over 7 days of display by near-infrared diffuse reflectance spectroscopy

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    Near-infrared diffuse reflectance spectroscopy (NIR-DRS) was utilized to develop an algorithm using approximately 18 wavelengths spanning 480 to 650 nm to determine oxymyoglobin (OxyMb), deoxymyoglobin (DeoxyMb), and metmyoglobin (MetMb) contents on beef longissimus lumborum muscles. Daily changes in subsurface myoglobin redox forms were evaluated for 7 d using NIR-DRS and compared with the surface color as assessed by a HunterLab MiniScan spectrophotometer as a reference modality. Both measurements revealed that MetMb increased steadily over the duration of display, showing high correlation (R2 = 0.91) between the 2 methods. Comparatively, whereas NIR-DRS revealed OxyMb to have decreased steadily over the period of display, the HunterLab MiniScan spectrophotometer indicated a much later onset of the apparent decrease of OxyMb, resulting in a moderate correlation (R2 = 0.64) between the 2 methods. No correlation was found between the 2 methods regarding the changes of DeoxyMb over the duration of display. The newly developed NIR-DRS algorithm has potential as an alternative method of color assessment in postrigor skeletal muscle.Electrical and Computer EngineeringAnimal and Food Science

    Digit-only sauropod pes trackways from China – evidence of swimming or a preservational phenomenon?

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    For more than 70 years unusual sauropod trackways have played a pivotal role in debates about the swimming ability of sauropods. Most claims that sauropods could swim have been based on manusonly or manus-dominated trackways. However none of these incomplete trackways has been entirely convincing, and most have proved to be taphonomic artifacts, either undertracks or the result of differential depth of penetration of manus and pes tracks, but otherwise showed the typical pattern of normal walking trackways. Here we report an assemblage of unusual sauropod tracks from the Lower Cretaceous Hekou Group of Gansu Province, northern China, characterized by the preservation of only the pes claw traces, that we interpret as having been left by walking, not buoyant or swimming, individuals. They are interpreted as the result of animals moving on a soft mud-silt substrate, projecting their claws deeply to register their traces on an underlying sand layer where they gained more grip during progression. Other sauropod walking trackways on the same surface with both pes and manus traces preserved, were probably left earlier on relatively firm substrates that predated the deposition of soft mud and silt . Presently, there is no convincing evidence of swimming sauropods from their trackways, which is not to say that sauropods did not swim at all

    Mixed methods to explore factors associated with the decline of patients in the methadone maintenance treatment program in Shanghai, China

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    BACKGROUND: This study was to characterize the Methadone Maintenance Treatment (MMT) in Shanghai, China, and to explore factors associated with the decline of patients in MMT during 2005-2016. METHODS: Both qualitative and quantitative methods were used in this study. Based on the data from Shanghai Centers for Disease Control (CDC), we described the changes in the number of patients who received MMT, and new enrollment each year from 2005 to 2016. Focus groups were conducted with 22 patients, and in-depth interviews were conducted with 9 service providers. RESULTS: Quantitative data demonstrate that the number of new enrollment began to decline in 2009, and the number of patients receiving MMT began to decline in 2012. The main reasons for dropout include (1) discontinuing medication due to unknown reasons (25%), (2) criminal activities other than drug-related crimes (20%), (3) relapse to heroin use (16%), and (4) physical disease (10%). Qualitative assessment results indicate that the major reasons for the decline of patients in MMT are as follows: (1) the increase of Amphetamine-type stimulants (ATS) use in recent years, (2) limited knowledge about MMT in both patients and MMT staff, (3) complicated enrollment criteria, and (4) discrimination against drug use. CONCLUSION: Various reasons to explain the decline of patients in MMT in Shanghai, China, were identified. Government agencies, service providers, and other stakeholders need to work together and overcome identified barriers to support MMT programs in China

    Cancellation of coherent artifacts in optical coherence tomography imaging

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    Coherent artifacts in optical coherence tomography ͑OCT͒ images can severely degrade image quality by introducing false targets if no targets are present at the artifact locations. Coherent artifacts can also add constructively or destructively to the targets that are present at the artifact locations. This constructive or destructive interference will result in cancellation of the true targets or in display of incorrect echo amplitudes of the targets. We introduce the use of a nonlinear deconvolution algorithm, CLEAN, to cancel coherent artifacts in OCT images of extracted human teeth. The results show that CLEAN can reduce the coherent artifacts to the noise background, sharpen the air-enamel and enamel-dentin interfaces, and improve the image contrast

    Two-dimensional SIR epidemics with long range infection

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    We extend a recent study of susceptible-infected-removed epidemic processes with long range infection (referred to as I in the following) from 1-dimensional lattices to lattices in two dimensions. As in I we use hashing to simulate very large lattices for which finite size effects can be neglected, in spite of the assumed power law p(x)xσ2p({\bf x})\sim |{\bf x}|^{-\sigma-2} for the probability that a site can infect another site a distance vector x{\bf x} apart. As in I we present detailed results for the critical case, for the supercritical case with σ=2\sigma = 2, and for the supercritical case with 0<σ<20< \sigma < 2. For the latter we verify the stretched exponential growth of the infected cluster with time predicted by M. Biskup. For σ=2\sigma=2 we find generic power laws with σ\sigma-dependent exponents in the supercritical phase, but no Kosterlitz-Thouless (KT) like critical point as in 1-d. Instead of diverging exponentially with the distance from the critical point, the correlation length increases with an inverse power, as in an ordinary critical point. Finally we study the dependence of the critical exponents on σ\sigma in the regime 0<σ<20<\sigma <2, and compare with field theoretic predictions. In particular we discuss in detail whether the critical behavior for σ\sigma slightly less than 2 is in the short range universality class, as conjectured recently by F. Linder {\it et al.}. As in I we also consider a modified version of the model where only some of the contacts are long range, the others being between nearest neighbors. If the number of the latter reaches the percolation threshold, the critical behavior is changed but the supercritical behavior stays qualitatively the same.Comment: 14 pages, including 29 figure

    Kramers-Kronig relation of graphene conductivity

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    Utilizing a complete Lorentz-covariant and local-gauge-invariant formulation, we discuss graphene response to arbitrary external electric field. The relation, which is called as Kramers-Kr(\ddot{o})nig relation in the paper, between imaginary part and real part of ac conductivity is given. We point out there exists an ambiguity in the conductivity computing, attributed to the wick behavior at ultraviolet vicinity. We argue that to study electrical response of graphene completely, non-perturbational contribution should be considered.Comment: 7 page
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