25,538 research outputs found
Unique Mass Texture for Quarks and Leptons
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, , ,
, lies in the range (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
rules out all of them. In the texture 4
zeros case, we find that there is a unique texture structure for and
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
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
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
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
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.)
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
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
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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LENS® and SFF: Enabling Technologies for Optimized Structures
Optimized, lightweight, high-strength structures are needed in many applications from aerospace
to automotive. In pursuit of such structures, there have been proposed analytical solutions and
some specialized FEA solutions for specific structures such as automobile frames. However,
generalized 3D optimization methods have been unavailable for use by most designers.
Moreover, in the cases where optimized structural solutions are available, they are often hollow,
curving, thin wall structures that cannot be fabricated by conventional manufacturing methods.
Researchers at Sandia National Laboratories and the University of Rhode Island teamed to solve
these problems. The team has been pursuing two methods of optimizing models for generalized
loading conditions, and also has been investigating the methods needed to fabricate these
structures using Laser Engineered Net Shaping™ (LENS®) and other rapid prototyping
methods. These solid freeform fabrication (SFF) methods offer the unique ability to make
hollow, high aspect ratio features out of many materials. The manufacturing development
required for LENS to make these complex structures has included the addition of rotational axes
to Sandia’s LENS machine bringing the total to 5 controlled axes. The additional axes have
required new efforts in process planning. Several of the unique structures that are only now
possible through the use of SFF technology are shown as part of the discussion of this exciting
new application for SFF.Mechanical Engineerin
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