75,472 research outputs found

    Epigenomes in Cardiovascular Disease.

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    If unifying principles could be revealed for how the same genome encodes different eukaryotic cells and for how genetic variability and environmental input are integrated to impact cardiovascular health, grand challenges in basic cell biology and translational medicine may succumb to experimental dissection. A rich body of work in model systems has implicated chromatin-modifying enzymes, DNA methylation, noncoding RNAs, and other transcriptome-shaping factors in adult health and in the development, progression, and mitigation of cardiovascular disease. Meanwhile, deployment of epigenomic tools, powered by next-generation sequencing technologies in cardiovascular models and human populations, has enabled description of epigenomic landscapes underpinning cellular function in the cardiovascular system. This essay aims to unpack the conceptual framework in which epigenomes are studied and to stimulate discussion on how principles of chromatin function may inform investigations of cardiovascular disease and the development of new therapies

    Exploration of the memory effect on the photon-assisted tunneling via a single quantum dot: A generalized Floquet theoretical approach

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    The generalized Floquet approach is developed to study memory effect on electron transport phenomena through a periodically driven single quantum dot in an electrode-multi-level dot-electrode nanoscale quantum device. The memory effect is treated using a multi-function Lorentzian spectral density (LSD) model that mimics the spectral density of each electrode in terms of multiple Lorentzian functions. For the symmetric single-function LSD model involving a single-level dot, the underlying single-particle propagator is shown to be related to a 2 x 2 effective time-dependent Hamiltonian that includes both the periodic external field and the electrode memory effect. By invoking the generalized Van Vleck (GVV) nearly degenerate perturbation theory, an analytical Tien-Gordon-like expression is derived for arbitrary order multi- photon resonance d.c. tunneling current. Numerically converged simulations and the GVV analytical results are in good agreement, revealing the origin of multi- photon coherent destruction of tunneling and accounting for the suppression of the staircase jumps of d.c. current due to the memory effect. Specially, a novel blockade phenomenon is observed, showing distinctive oscillations in the field-induced current in the large bias voltage limit

    Search for C=+C=+ charmonium and bottomonium states in e+eγ+Xe^+e^-\to \gamma+ X at B factories

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    We study the production of C=+C=+ charmonium states XX in e+eγ+Xe^+e^-\to \gamma + X at B factories with X=ηc(nS)X=\eta_c(nS) (n=1,2,3), χcJ(mP)\chi_{cJ}(mP) (m=1,2), and 1D2(1D)^1D_2(1D). In the S and P wave case, contributions of tree-QED with one-loop QCD corrections are calculated within the framework of nonrelativistic QCD(NRQCD) and in the D-wave case only the tree-QED contribution are considered. We find that in most cases the QCD corrections are negative and moderate, in contrast to the case of double charmonium production e+eJ/ψ+Xe^+e^-\to J/\psi + X, where QCD corrections are positive and large in most cases. We also find that the production cross sections of some of these states in e+eγ+Xe^+e^-\to \gamma + X are larger than that in e+eJ/ψ+Xe^+e^-\to J/\psi + X by an order of magnitude even after the negative QCD corrections are included. So we argue that search for the X(3872), X(3940), Y(3940), and X(4160) in e+eγ+Xe^+e^-\to \gamma + X at B factories may be helpful to clarify the nature of these states. For completeness, the production of bottomonium states in e+ee^+e^- annihilation is also discussed.Comment: 13pages, 4 figure

    Modifikasi dan Perbaikan Kinerja Alat Pengiris Mayang Kelapa untuk Menyadap Nira

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    Tanaman kelapa banyak ditemukan didaerah tropis dan subtropis. Penyadapan nira tanaman kelapa masih dilakukan secara tradisional. Tukang sadap memanjat pohon kelapa, mengiris mayang muda, dan menampung nira dengan wadah dari bambu. Memanjat pohon kelapa tiap hari beresiko akan jatuh dari atas pohon. Penelitian ini bertujuan memodifikasi membuat dan menguji alat mengiris mayang kelapa yang dapat dioperasikan dari bawah pohon kelapa. Pembuatan alat pengiris mayang kelapa melalui proses rancangan konseptual, rancangan perwujudan, pabrikasi and pengujian alat di lapang. Hasil penelitian menunjukkan bahwa beban tarik untuk mengiris mayang sebesar adalah 12-20 kg gaya. nira yang dihasilkan dengan cara mengiris mayang dengan alat adalah 0,73 -1,41 liter. sementara penyadapan nira yang dihasilkan dengan tradisional sebesar 0,97-2,34 liter. Penyadapan dilakukan selama 21 hari. Pisau yang tajam, sudut pisau nol derajat, dan sistem pengungkit merupakan tiga kondisi untuk mengurangi beban tarik saat pengiris mayang kelapa

    Towards Vulnerability Discovery Using Staged Program Analysis

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    Eliminating vulnerabilities from low-level code is vital for securing software. Static analysis is a promising approach for discovering vulnerabilities since it can provide developers early feedback on the code they write. But, it presents multiple challenges not the least of which is understanding what makes a bug exploitable and conveying this information to the developer. In this paper, we present the design and implementation of a practical vulnerability assessment framework, called Melange. Melange performs data and control flow analysis to diagnose potential security bugs, and outputs well-formatted bug reports that help developers understand and fix security bugs. Based on the intuition that real-world vulnerabilities manifest themselves across multiple parts of a program, Melange performs both local and global analyses. To scale up to large programs, global analysis is demand-driven. Our prototype detects multiple vulnerability classes in C and C++ code including type confusion, and garbage memory reads. We have evaluated Melange extensively. Our case studies show that Melange scales up to large codebases such as Chromium, is easy-to-use, and most importantly, capable of discovering vulnerabilities in real-world code. Our findings indicate that static analysis is a viable reinforcement to the software testing tool set.Comment: A revised version to appear in the proceedings of the 13th conference on Detection of Intrusions and Malware & Vulnerability Assessment (DIMVA), July 201

    Hsc66 substrate specificity is directed toward a discrete region of the iron-sulfur cluster template protein IscU

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    Hsc66 and Hsc20 comprise a specialized chaperone system important for the assembly of iron-sulfur clusters in Escherchia coli. Only a single substrate, the Fe/S template protein IscU, has been identified for the Hsc66/Hsc20 system, but the mechanism by which Hsc66 selectively binds IscU is unknown. We have investigated Hsc66 substrate specificity using phage display and a peptide array of IscU. Screening of a heptameric peptide phage display library revealed that Hsc66 prefers peptides with a centrally located Pro-Pro motif. Using a cellulose-bound peptide array of IscU we determined that Hsc66 interacts specifically with a region (residues 99-103, LPPVK) that is invariant among all IscU family members. A synthetic peptide (ELPPVKIHC) corresponding to IscU residues 98-106 behaves in a similar manner to native IscU, stimulating the ATPase activity of Hsc66 with similar affinity as IscU, preventing Hsc66 suppression of bovine rhodanese aggregation, and interacting with the peptide-binding domain of Hsc66. Unlike native IscU, however, the synthetic peptide is not bound by Hsc20 and does not synergistically stimulate Hsc66 ATPase activity with Hsc20. Our results indicate that Hsc66 and Hsc20 recognize distinct regions of IscU and further suggest that Hsc66 will not bind LPPVK motifs with high affinity in vivo unless they are in the context of native IscU and can be directed to Hsc66 by Hsc20

    Fermion masses in the economical 3-3-1 model

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    We show that, in frameworks of the economical 3-3-1 model, all fermions get masses. At the tree level, one up-quark and two down-quarks are massless, but the one-loop corrections give all quarks the consistent masses. This conclusion is in contradiction to the previous analysis in which, the third scalar triplet has been introduced. This result is based on the key properties of the model: First, there are three quite different scales of vacuum expectation values: \om \sim {\cal O}(1) \mathrm{TeV}, v \approx 246 \mathrm{GeV} and uO(1)GeV u \sim {\cal O}(1) \mathrm{GeV}. Second, there exist two types of Yukawa couplings with different strengths: the lepton-number conserving couplings hh's and the lepton-number violating ones ss's satisfying the condition in which the second are much smaller than the first ones: sh s \ll h. With the acceptable set of parameters, numerical evaluation shows that in this model, masses of the exotic quarks also have different scales, namely, the UU exotic quark (qU=2/3q_U = 2/3) gains mass mU700m_U \approx 700 GeV, while the D_\al exotic quarks (q_{D_\al} = -1/3) have masses in the TeV scale: m_{D_\al} \in 10 \div 80 TeV.Comment: 20 pages, 8 figure
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