11,477 research outputs found

    An Optimal Algorithm for the Maximum-Density Segment Problem

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    We address a fundamental problem arising from analysis of biomolecular sequences. The input consists of two numbers wminw_{\min} and wmaxw_{\max} and a sequence SS of nn number pairs (ai,wi)(a_i,w_i) with wi>0w_i>0. Let {\em segment} S(i,j)S(i,j) of SS be the consecutive subsequence of SS between indices ii and jj. The {\em density} of S(i,j)S(i,j) is d(i,j)=(ai+ai+1+...+aj)/(wi+wi+1+...+wj)d(i,j)=(a_i+a_{i+1}+...+a_j)/(w_i+w_{i+1}+...+w_j). The {\em maximum-density segment problem} is to find a maximum-density segment over all segments S(i,j)S(i,j) with wminwi+wi+1+...+wjwmaxw_{\min}\leq w_i+w_{i+1}+...+w_j \leq w_{\max}. The best previously known algorithm for the problem, due to Goldwasser, Kao, and Lu, runs in O(nlog(wmaxwmin+1))O(n\log(w_{\max}-w_{\min}+1)) time. In the present paper, we solve the problem in O(n) time. Our approach bypasses the complicated {\em right-skew decomposition}, introduced by Lin, Jiang, and Chao. As a result, our algorithm has the capability to process the input sequence in an online manner, which is an important feature for dealing with genome-scale sequences. Moreover, for a type of input sequences SS representable in O(m)O(m) space, we show how to exploit the sparsity of SS and solve the maximum-density segment problem for SS in O(m)O(m) time.Comment: 15 pages, 12 figures, an early version of this paper was presented at 11th Annual European Symposium on Algorithms (ESA 2003), Budapest, Hungary, September 15-20, 200

    Fire responses and resistance of concrete-filled steel tubular frame structures

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    This paper presents the results of dynamic responses and fire resistance of concretefilled steel tubular (CFST) frame structures in fire conditions by using non-linear finite element method. Both strength and stability criteria are considered in the collapse analysis. The frame structures are constructed with circular CFST columns and steel beams of I-sections. In order to validate the finite element solutions, the numerical results are compared with those from a fire resistance test on CFST columns. The finite element model is then adopted to simulate the behaviour of frame structures in fire. The structural responses of the frames, including critical temperature and fire-resisting limit time, are obtained for the ISO-834 standard fire. Parametric studies are carried out to show their influence on the load capacity of the frame structures in fire. Suggestions and recommendations are presented for possible adoption in future construction and design of these structures

    Relative entropy of entanglement of a kind of two qubit entangled states

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    We in this paper strictly prove that some block diagonalizable two qubit entangled state with six none zero elements reaches its quantum relative entropy entanglement by the a separable state having the same matrix structure. The entangled state comprises local filtering result state as a special case.Comment: 5 page

    ROS signaling and its involvement in abiotic stress with emphasis on heat stress-driven anther sterility in plants

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    ROS signaling and its involvement in abiotic stress with emphasis on heat stress-driven anther sterility in plants, Crop and Environment, https://doi. Abstract 12 With global warming, crop plants are challenged by heat stress during reproductive growth, 13 leading to male sterility and yield reduction. The balance between reactive oxygen species (ROS) 14 generation and scavenging is disrupted by stress, resulting in oxidative stress, which is harmful to 15 crop growth. However, recent advances have shown that ROS signaling via proteins that sense the 16 redox state is positive for plant performance under stress. ROS signaling is also involved in 17 regulating anther development, such as timely tapetum degeneration. We summarize recent progress 18 in uncovering the mechanism of heat stress effects on ROS homeostasis and discuss the relationship 19 between oxidative stress and metabolic disorder, which is often observed during anther development 20 under heat stress. We propose experimental and breeding strategies to improve field crop tolerance 21 to heat stress. 2

    Neutrino oscillations in Kerr-Newman space-time

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    The mass neutrino oscillation in Kerr-Newman(K-N) space-time is studied in the plane θ=θ0\theta=\theta_{0}, and the general equations of oscillation phases are given. The effect of the rotation and electric charge on the phase is presented. Then, we consider three special cases: (1) The neutrinos travel along the geodesics with the angular momentum L=aEL=aE in the equatorial plane. (2) The neutrinos travel along the geodesics with L=0 in the equatorial plane. (3) The neutrinos travel along the radial geodesics at the direction θ=0\theta=0. At last, we calculate the proper oscillation length in the K-N space time. The effect of the gravitational field on the oscillation length is embodied in the gravitational red shift factor. When the neutrino travels out of the gravitational field, the blue shift of the oscillation length takes place. We discussed the variation of the oscillation length influenced by the gravitational field strength, the rotation a2a^{2} and charge QQ.Comment: 20 pages, no figure

    Magnetization and Magnetotransport of LnBaCo2O5.5 (Ln=Gd, Eu) Single Crystals

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    The magnetization, resistivity and magnetoresistance (MR) of single crystals of GdBaCo2O5.5 and EuBaCo2O5.5 are measured over a wide range of dc magnetic fields (up to 30 T) and temperature. In LnBaCo2O5.5 (Ln=Gd, Eu), the Co-ions are trivalent and can exist in three spin states, namely, the S=0 low spin state (LS), the S= 1 intermediate spin state (IS) and the S=2 high spin state (HS). We confirm that GdBaCo2O5.5 and EuBaCo2O5.5 have a metal-insulator transition accompanied by a spin-state transition at TMI >> 365 and 335 K, respectively. The data suggest an equal ratio of LS (S=0) and IS (S=1) Co3+ ions below TMI, with no indication of additional spin state transitions. The low field magnetization shows a transition to a highly anisotropic ferromagnetic phase at 270 K, followed by another magnetic transition to an antiferromagnetic phase at a slightly lower temperature. The magnetization data are suggestive of weak correlations between the Gd-spins but no clear signature of ordering is seen for T > 2 K. Significant anisotropy between the a-b plane and c axis was observed in magnetic and magnetotransport properties for both compounds. For GdBaCo2O5.5, the resistivity and MR data imply a strong correlation between the spin-order and charge carriers. For EuBaCo2O5.5, the magnetic phase diagram is very similar to its Gd counterpart, but the low-T MR with current flow in the ab plane is positive rather than negative as for Gd. The magnitude and the hysteresis of the MR for EuBaCo2O5.5 decrease with increasing temperature, and at higher T the MR changes sign and becomes negative. The difference in the behavior of both compounds may arise from a small valence admixture in the nonmagnetic Eu ions, i.e. a valence slightly less than 3+.Comment: Accepted for publication in PR

    Hall Drag in Correlated Double Layer Quantum Hall Systems

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    We show that in the limit of zero temperature, double layer quantum Hall systems exhibit a novel phenomena called Hall drag, namely a current driven in one layer induces a voltage drop in the other layer, in the direction perpendicular to the driving current. The two-by-two Hall resistivity tensor is quantized and proportional to the K{\bf K} matrix that describes the topological order of the quantum Hall state, even when the K{\bf K} matrix contains a zero eigenvalue, in which case the Hall conductivity tensor does not exist. Relation between the present work and previous ones is also discussed.Comment: 4 pages, 1 eps figure. Accepted in PRB, R

    Advances on the Antioxidant Peptides from Nuts: A Narrow Review

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    Antioxidant peptides extracted from natural foods have been studied for their potential use in the development of additives, nutraceuticals, and therapeutic agents. Nut proteins are considered an excellent source of plant-derived proteins for the human diet, due to their high protein content and digestibility of up to 86.22%. Furthermore, compared with grain and soybean proteins, nut proteins have a special amino acid composition, which makes their protein structure different, and promotes their disparate functional characteristics and great bioactivity potential. This review presents the most remarkable studies on antioxidant peptides from nuts, to gain insights into feasible production methods, different evaluation indexes within in vivo or in vitro systems, high bioavailability, and the complex structure-activity relationship resulting from the particularity of their protein structure and amino acid composition. Previously published studies mainly focused on the effects of the production methods/processes of nut-derived peptides on antioxidant activity, and proved that nut-extracted antioxidant peptides can resist the degradation of acid, alkali, and gastrointestinal enzymes, have high antioxidant activity in vitro and in vivo, and also have the potential to cross small intestinal epithelial cells in a stable and integral manner. However, the structure-activity relationship of antioxidant peptides from nuts has not been fully established, and the structure information of antioxidant peptides obtained from various nut protein sources is still unclear. The findings presented in this review can be used to provide the theoretical basis for the design and production of nut-derived antioxidant peptides

    Measurement of the final states ωπ0\omega \pi^0, ρη\rho \eta, and ρη\rho \eta^{'} from \psip electromagnetic decays and \ee annihilations

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    Cross sections and form factors for \ee \to \wpi, ρη\rho\eta, and \rho\etap at center of mass energies of 3.650, 3.686, and 3.773 GeV are measured using data samples collected with the BESII detector at the BEPC. Also, the branching fractions of \psi(2S) \rar \wpi, ρη\rho\eta, and \rho\etap are determined to be (1.870.62+0.68±0.28)×105(1.87^{+0.68}_{-0.62}\pm0.28)\times 10^{-5}, (1.780.62+0.67±0.17)×105(1.78^{+0.67}_{-0.62}\pm0.17)\times 10^{-5}, and (1.871.11+1.64±0.33)×105(1.87^{+1.64}_{-1.11}\pm0.33)\times10^{-5}, respectively.Comment: 8 pages, 4 figures, 4 table

    The Quantum Spin Hall Effect: Theory and Experiment

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    The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Recently, a new class of topological insulators has been proposed. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. In two dimensions the helical edge states give rise to the quantum spin Hall (QSH) effect, in the absence of any external magnetic field. Here we review a recent theory which predicts that the QSH state can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the band structure changes from a normal to an "inverted" type at a critical thickness dcd_c. We present an analytical solution of the helical edge states and explicitly demonstrate their topological stability. We also review the recent experimental observation of the QSH state in HgTe/(Hg,Cd)Te quantum wells. We review both the fabrication of the sample and the experimental setup. For thin quantum wells with well width dQW<6.3d_{QW}< 6.3 nm, the insulating regime shows the conventional behavior of vanishingly small conductance at low temperature. However, for thicker quantum wells (dQW>6.3d_{QW}> 6.3 nm), the nominally insulating regime shows a plateau of residual conductance close to 2e2/h2e^2/h. The residual conductance is independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance is destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, dc=6.3d_c= 6.3 nm, is also independently determined from the occurrence of a magnetic field induced insulator to metal transition.Comment: Invited review article for special issue of JPSJ, 32 pages. For higher resolution figures see official online version when publishe
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