25,538 research outputs found

    Unique Mass Texture for Quarks and Leptons

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    Texture specific quark mass matrices which are hermitian and hierarchical are examined in detail . In the case of texture 6 zeros matrices, out of sixteen possibilities examined by us, none is able to fit the low energy data (LED), for example, Vus=0.2196±0.0023V_{us} = 0.2196 \pm 0.0023, Vcb=0.0395±0.0017V_{cb} = 0.0395 \pm 0.0017, VubVcb=0.08±0.02\frac{V_{ub}}{V_{cb}} = 0.08 \pm 0.02, VtdV_{td} lies in the range 0.0040.0130.004 - 0.013 (PDG). Similarly none of the 32 texture 5 zeros mass matrices considered is able to reproduce LED. In particular, the latest data from LEP regarding Vub/Vcb(=0.093±0.016)|V_{ub}|/|V_{cb}|(=0.093\pm0.016) rules out all of them. In the texture 4 zeros case, we find that there is a unique texture structure for UU and DD mass matrices which is able to fit the data.Comment: 12 pages, LaTeX,some changes in the references,minor changes in the text,to appear in Phys Rev D(Rapid communications

    A five year outbreak of methicillin-susceptible Staphylococcus aureus phage type 53,85 in a regional neonatal unit

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    We identified a 5-year outbreak of a methicillin-susceptible Staphylococcus aureus (MSSA) strain, affecting 202 babies on a neonatal unit, by routine weekly phage typing all S. aureus isolates. Multiple staged control measures including strict emphasis on hand hygiene, environmental and staff surveillance sampling, and application of topical hexachlorophane powder failed to end the outbreak. S. aureus PT 53,85 (SA5385) was found on opened packs of Stomahesive®, used as a neonatal skin protectant. Only following the implementation of aseptic handling of Stomahesive®, and the use of topical mupirocin for staff nasal carriers of SA5385, and for babies colonized or infected with S. aureus, did the isolation rate of SA5385 decline. DNA fingerprinting indicated that [gt-or-equal, slanted]95% of SA5385 isolates were clonal. In vitro death rates of SA5385 on Stomahesive® with human serum were significantly lower than on Stomahesive® alone (P = 0·04), and on cotton sheet with serum (P = 0·04), highlighting the potential of this material as a survival niche. Phage typing remains a valuable, inexpensive and simple method for monitoring nosocomial MSSA infection

    Domains of invasion organelle proteins from apicomplexan parasites are homologous with the Apple domains of blood coagulation factor XI and plasma pre-kallikrein and are members of the PAN module superfamily

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    AbstractMicronemes are specialised organelles, found in all apicomplexan parasites, which secrete molecules that are essential for parasite attachment to and invasion of host cells. Regions of several microneme proteins have sequence similarity to the Apple domains (A-domains) of blood coagulation factor XI (FXI) and plasma pre-kallikrein (PK). We have used mass spectrometry on a recombinant-expressed, putative A-domain from the microneme protein EtMIC5 from Eimeria tenella, to demonstrate that three intramolecular disulphide bridges are formed. These bridges are analogous to those that stabilise A-domains in FXI and PK. The data confirm that the apicomplexan domains are structural homologues of A-domains and are therefore novel members of the PAN module superfamily, which also includes the N-terminal domains of members of the plasminogen/hepatocyte growth factor family. The role of A-domains/PAN modules in apicomplexan parasites is not known, but their presence in the microneme suggests that they may be important for mediating protein–protein or protein–carbohydrate interactions during parasite attachment and host cell invasion

    Laser frequency stabilization to a single ion

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    A fundamental limit to the stability of a single-ion optical frequency standard is set by quantum noise in the measurement of the internal state of the ion. We discuss how the interrogation sequence and the processing of the atomic resonance signal can be optimized in order to obtain the highest possible stability under realistic experimental conditions. A servo algorithm is presented that stabilizes a laser frequency to the single-ion signal and that eliminates errors due to laser frequency drift. Numerical simulations of the servo characteristics are compared to experimental data from a frequency comparison of two single-ion standards based on a transition at 688 THz in 171Yb+. Experimentally, an instability sigma_y(100 s)=9*10^{-16} is obtained in the frequency difference between both standards.Comment: 15 pages, 5 figures, submitted to J. Phys.

    Calcium binding activity of the epidermal growth factor-like domains of the apicomplexan microneme protein EtMIC4

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    Microneme proteins are secreted from apicomplexan parasites during invasion of host cells and they play crucial roles in parasite-host cell adhesion. EtMIC4 is a 240 kDa transmembrane protein from Eimeria tenella that contains 31 tandemly arranged epidermal growth factor (EGF), like repeats within its extracellular domain. The majority of these repeats have calcium binding (cb) consensus sequences. Little is known about cbEGFs in apicomplexan parasites but their presence in microneme proteins suggests that they may contribute to parasite-host interactions. To investigate the potential role of cbEGFs we have expressed and correctly refolded a cbEGF triplet from EtMIC4 (cbEGF7-9) and demonstrated that this triplet binds calcium. Circular dichroism spectroscopic analysis of cbEGF7-9 demonstrates that the molecule undergoes a gradual change in conformation with increasing levels of calcium. In the presence of calcium, the triplet becomes resistant to proteolytic degradation by a variety of proteases, a characteristic feature of cbEGF repeats from higher eukaryotic proteins, such as fibrillin, suggesting that calcium binding induces the formation of a rigid conformation. Moreover, mass spectrometric mapping of the cleavage sites that are protected by calcium shows that these sites are located both close to and distant from the calcium binding sites, indicating that protection is not due to steric hindrance by calcium ions, but rather due to the overall conformation adopted by the triplet in the presence of calcium. Thus, the tandemly-arranged cbEGF repeats within EtMIC4 provide a mechanism whereby, in the calcium-rich extracellular environment, the molecule could adopt a protease-resistant, rigid structure that could favour its interaction with host cell ligands

    Effect of integrated nitrogen management on NPK uptake in basmati rice (Oryza sativa L.)

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    A field experiment entitled NPK uptake influenced by integrated nitrogen management in basmati rice (Oryza sativa L.) was conducted at Punjab Agricultural University, Ludhiana during kharif 2010. The experiment was conducted in randomized block design with 13 treatment combinations of chemical fertilizer, green manuring (GM) with Crotalaria juncea, farmyard manure (FYM) and organic preparations [OP (Jeevamrit and Panchagavya)] in four replications. The highest grain yield (34.9±0.54 q ha-1 ) was obtained with combined application of FYM and 50 per cent of recommended nitrogen (RN) followed by GM+FYM+OP (33.7 q ha-1 ) and GM+FYM (33.4±0.99 q ha-1 ). Straw yield (63.1 q ha-1 ) increased significantly (P<0.01) in treatment where FYM combined with 50 per cent of RN was applied. Among different nitrogen management treatments, the maximum N, P and K uptake in grain and straw were observed under treatment T8 (FYM +50 per cent of RN) viz. integrated nitrogen treatment followed by T11 (GM+FYM+OP) and T9 (GM+FYM). Thus, combined application of FYM @ 19.76 t ha-1- with reduced fertilizer dose (50 % of RN) increased the yield and NPK uptake in basmati rice

    Prescient, inconsistent, and ignorant: Commentary on the Dispensation of dynamite

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    Comments on the article The Dispensation of Dynamite (1883, March 16) (see record 2018-63621-005). The Dispensation of Dynamite (1883, March 16) is equal parts prescient, inconsistent, ignorant, and devoid of true context. The authors try to contextualize aspects of Dispensation’s reporting, add some correctives to erroneous aspects, and draw upon contemporary debates within terrorism studies, as well as recent terrorist attacks. Dispensation reports the day after coordinated

    EXPO-12: Development and validation of the Exposure to Violent Extremism Scale

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    Objective: This study details the development and validation of the 12-item Exposure to Violent Extremism Scale (EXPO-12). We aimed to undertake a transparent and robust process of scale development to present a tool to facilitate research on the relationship between exposure and violent extremism. / Method: First, we generated an initial item pool and evaluated items via expert feedback (n = 6) and a task designed to assess item comprehension (n = 13; Study 1). Second, we explored the underlying factor structure with exploratory factor analysis (EFA) and evaluated item characteristics with item response theory (IRT) in a representative sample of the U.K. population (n = 1, 509; Study 2). Finally, we sought to replicate the factor structure proposed by Study 2 via confirmatory factor analysis (CFA) and examined convergent validity with a related construct, violent extremist intentions (n = 1, 475; Study 3). / Results: Study 1 resulted in a preliminary pool of 40 items. Study 2 used EFA to establish a four-factor structure consisting of 21 items. IRT further reduced the item pool by evaluating differential item functioning, discrimination, and location parameters, resulting in EXPO-12. Study 3 replicated the factor structure proposed in Study 2 via CFA. EXPO-12 demonstrated good convergent validity with violent extremist intentions. / Conclusion: EXPO-12 is presented as a preliminarily validated measure of the concept, alongside its limitations. The scale’s main implication is as a tool to facilitate research to unpack the complexity and nuances of the relationship between exposure and violent extremism
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