2,102 research outputs found

    Apolipoprotein AIV gene variant S347 is associated with increased risk of coronary heart disease and lower plasma apolipoprotein AIV levels

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    The impact of common variants in the apolipoprotein gene cluster (APOC3-A4-A5) on prospective coronary heart disease (CHD) risk was examined in healthy UK men. Of the 2808 men followed over 9 years, 187 had a clinically defined CHD event. Examination of 9 single nucleotide polymorphisms (SNPs) in this group revealed that homozygotes for APOA4 S347 had significantly increased risk of CHD [hazard ratio (HR) of 2.07 (95%CI 1.04 to 4.12)], whereas men homozygous for APOC3 1100T were protected [HR 0.28 (95%CI 0.09 to 0.87)]. In stepwise multiple regression analysis, after entering all the variants and adjusting for established risk factors APOA4 T347S alone remained in the model. Using all nine SNPs, the highest risk-estimate haplotypes carried APOA4 S347 and rare alleles of the two flanking intergenic markers. The protective effect of APOC3 1100T could be explained by negative linkage disequilibrium with these alleles. To determine the association of APOA4 T347S with apoAIV levels, the relationship was examined in 1600 healthy young European men and women. S347 homozygotes had significantly lower apoAIV plasma levels (13.64±0.59 mg/dL) compared with carriers of the T347 allele (14.90±0.12 mg/dL) (P=0.035). These results demonstrate that genetic variation in and around APOA4, independent of the effects of triglyceride, is associated with risk of CHD and apoAIV levels, supporting an antiatherogenic role for apoAIV

    Spin-based quantum information processing with semiconductor quantum dots and cavity QED

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    A quantum information processing scheme is proposed with semiconductor quantum dots located in a high-Q single mode QED cavity. The spin degrees of freedom of one excess conduction electron of the quantum dots are employed as qubits. Excitonic states, which can be produced ultrafastly with optical operation, are used as auxiliary states in the realization of quantum gates. We show how properly tailored ultrafast laser pulses and Pauli-blocking effects, can be used to achieve a universal encoded quantum computing.Comment: RevTex, 2 figure

    Functional analysis of the interaction of the human immunodeficiency virus type 1 Rev nuclear export signal with its cofactors

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    AbstractHuman immunodeficiency virus type 1 (HIV-1) Rev-mediated nuclear export of viral RNAs involves the interaction of its leucine-rich nuclear export sequence (NES) with nuclear cofactors. In yeast two-hybrid screens of a human lymph node derived cDNA expression library, we identified the human nucleoporin Nup98 as a highly specific and potent interactor of the Rev NES. Using an extensive panel of nuclear export positive and negative mutants of the functionally homologous NESs of the HIV-1 Rev, human T cell leukemia virus type 1 (HTLV-1) Rex, and equine infectious anemia virus (EIAV) Rev proteins, physiologically significant interaction of hNup98 with the various NESs was demonstrated. Missense mutations in the yeast nuclear export factor Crm1p that abrogated Rev NES interaction with the XXFG repeat-containing nucleoporin, Rab/hRIP, had minimal effects on the interaction of GLFG repeat-containing hNup98. Functional analysis of Nup98 domains required for nuclear localization demonstrated that the entire ORF was required for efficient incorporation into the nuclear envelope. A putative nuclear localization signal was identified downstream of the GLFG repeat region. Whereas overexpression of both full-length Nup98 and the amino-terminal GLFG repeat region, but not the unique carboxy-terminal region, induced significant suppression of HIV unspliced RNA export, lower levels of exogenous Nup98 expression resulted in a relatively modest increase in unspliced RNA export. These results suggest a physiological role for hNup98 in modulating Rev-dependent RNA export during HIV infection

    Grover search with pairs of trapped ions

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    The desired interference required for quantum computing may be modified by the wave function oscillations for the implementation of quantum algorithms[Phys.Rev.Lett.84(2000)1615]. To diminish such detrimental effect, we propose a scheme with trapped ion-pairs being qubits and apply the scheme to the Grover search. It can be found that our scheme can not only carry out a full Grover search, but also meet the requirement for the scalable hot-ion quantum computing. Moreover, the ion-pair qubits in our scheme are more robust against the decoherence and the dissipation caused by the environment than single-particle qubits proposed before.Comment: RevTe

    Two-tape finite automata with quantum and classical states

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    {\it Two-way finite automata with quantum and classical states} (2QCFA) were introduced by Ambainis and Watrous, and {\it two-way two-tape deterministic finite automata} (2TFA) were introduced by Rabin and Scott. In this paper we study 2TFA and propose a new computing model called {\it two-way two-tape finite automata with quantum and classical states} (2TQCFA). First, we give efficient 2TFA algorithms for recognizing languages which can be recognized by 2QCFA. Second, we give efficient 2TQCFA algorithms to recognize several languages whose status vis-a-vis 2QCFA have been posed as open questions, such as Lsquare={anbn2nN}L_{square}=\{a^{n}b^{n^{2}}\mid n\in \mathbf{N}\}. Third, we show that {anbnknN}\{a^{n}b^{n^{k}}\mid n\in \mathbf{N}\} can be recognized by {\it (k+1)(k+1)-tape deterministic finite automata} ((k+1)(k+1)TFA). Finally, we introduce {\it kk-tape automata with quantum and classical states} (kkTQCFA) and prove that {anbnknN}\{a^{n}b^{n^{k}}\mid n\in \mathbf{N}\} can be recognized by kkTQCFA.Comment: 25 page

    Regulator of the mucoid phenotype A gene increases the virulent ability of extended-spectrum beta-lactamase-producing serotype non-K1/K2 Klebsiella pneumonia

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    BackgroundTo determine whether the presence of a capsule regulator gene [i.e., regulator of mucoid phenotype A (rmpA) gene] contributes to virulence on extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) with serotype non-K1/K2 strains.MethodsTwenty-eight ESBL-KP and non-ESBL-KP isolates were collected from the Tri-Service General Hospital (Taipei, Taiwan). The impact of the virulent rmpA gene in different capsular polysaccharide serotypes on ESBL-KP and non-ESBL-KP isolates was studied by a neutrophil phagocytosis reaction, a serum bactericidal assay, and an animal survival model.ResultsResistance to broad spectrum antibiotics was more prevalent in ESBL-KP strains than in non-ESBL-KP strains (p < 0.01). The ESBL-KP strains had different molecular patterns from non-ESBL-KP strains, based on pulsed-field gel electrophoresis. The frequency of serum-resistant isolates was the highest among ESBL-KP strains with rmpA (i.e., rmpA+) [71.4% (5/7)] than among of non-ESBL-KP rmpA+ strains [42.8% (6/14)], ESBL-KP strains without rmpA (rmpA−) [33.3% (7/21)], and non-ESBL-KP rmpA− strains [14.2% (2/14)]. The most significant increase in neutrophil resistance occurred in the ESBL-KP rmpA+ strains in comparison to the non-ESBL-KP rmpA+, ESBL-KP rmpA−, and non-ESBL-KP rmpA− strains (p < 0.01). The results of the animal survival model were compatible with the neutrophil phagocytosis reaction and serum bactericidal assay.ConclusionWe conclude that the pathogenic potential is greater in rmpA+ ESBL-KP strains than in rmpA– ESBL-KP and non-ESBL-KP strains

    Regulation of L-Selectin–mediated Rolling through Receptor Dimerization

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    L-selectin binding activity for its ligand expressed by vascular endothelium is rapidly and transiently increased after leukocyte activation. To identify mechanisms for upregulation and assess how this influences leukocyte/endothelial cell interactions, cell-surface dimers of L-selectin were induced using the coumermycin–GyrB dimerization strategy for cross-linking L-selectin cytoplasmic domains in L-selectin cDNA-transfected lymphoblastoid cells. Coumermycin- induced L-selectin dimerization resulted in an approximately fourfold increase in binding of phosphomanan monoester core complex (PPME), a natural mimic of an L-selectin ligand, comparable to that observed after leukocyte activation. Moreover, L-selectin dimerization significantly increased (by ∼700%) the number of lymphocytes rolling on vascular endothelium under a broad range of physiological shear stresses, and significantly slowed their rolling velocities. Therefore, L-selectin dimerization may explain the rapid increase in ligand binding activity that occurs after leukocyte activation and may directly influence leukocyte migration to peripheral lymphoid tissues or to sites of inflammation. Inducible oligomerization may also be a common mechanism for rapidly upregulating the adhesive or ligand-binding function of other cell-surface receptors

    Cement composites reinforced with surface modified coir fibers

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    An experimental investigation of coir mesh reinforced mortar (CMRM) is conducted using nonwoven coir mesh matting. The main parameters in this study are the fiber volume fraction (number of mesh layers) and fiber surface treatment with a wetting agent. The composites are subjected to the four-point bending test. The short-term mechanical properties of CMRM are discussed. Scanning electron micrograph analysis is used to observe the fiber&mdash;matrix interfacial characteristics. The results indicate that the addition of coir mesh to mortar significantly improves the composite post-cracking flexural stress, toughness, ductility, and toughness index, compared to plain mortar materials. The Albatex &copy; FFC wetting agent (2-ethylhexanol) can effectively improve water absorption of coir fiber and enhance the fiber&mdash;matrix bonding strength. These coir mesh reinforced composites may be useful in civil engineering applications.<br /

    Probing the Role of Magnetic-Field Variations in NOAA AR 8038 in Producing Solar Flare and CME on 12 May 1997

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    We carried out a multi-wavelength study of a CME and a medium-size 1B/C1.3 flare occurring on 12 May 1997. We present the investigation of magnetic-field variations in the NOAA Active Region 8038 which was observed on the Sun during 7--16 May 1997. Analyses of H{\alpha} filtergrams and MDI/SOHO magnetograms revealed continual but discrete surge activity, and emergence and cancellation of flux in this active region. The movie of these magnetograms revealed two important results that the major opposite polarities of pre-existing region as well as in the emerging flux region (EFR) were approaching towards each other and moving magnetic features (MMF) were ejecting out from the major north polarity at a quasi-periodicity of about ten hrs during 10--13 May 1997. These activities were probably caused by the magnetic reconnection in the lower atmosphere driven by photospheric convergence motions, which were evident in magnetograms. The magnetic field variations such as flux, gradient, and sunspot rotation revealed that free energy was slowly being stored in the corona. The slow low-layer magnetic reconnection may be responsible for this storage and the formation of a sigmoidal core field or a flux rope leading to the eventual eruption. The occurrence of EUV brightenings in the sigmoidal core field prior to the rise of a flux rope suggests that the eruption was triggered by the inner tether-cutting reconnection, but not the external breakout reconnection. An impulsive acceleration revealed from fast separation of the H{\alpha} ribbons of the first 150 seconds suggests the CME accelerated in the inner corona, which is consistent with the temporal profile of the reconnection electric field. In conclusion, we propose a qualitative model in view of framework of a solar eruption involving, mass ejections, filament eruption, CME, and subsequent flare.Comment: 8 figures, accepted for publication in Solar Physic
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