1,140 research outputs found

    1980 Farm Business Analysis Report General Crop Summary

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    Exact date of working paper unknown

    Do the constants of nature couple to strong gravitational fields?

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    Recently, white dwarf stars have found a new use in the fundamental physics community. Many prospective theories of the fundamental interactions of Nature allow traditional constants, like the fine structure constant α\alpha, to vary in some way. A study by Berengut et al. (2013) used the Fe/Ni V line measurements made by Preval et al. (2013) from the hot DA white dwarf G191-B2B, in an attempt to detect any variation in α\alpha. It was found that the Fe V lines indicated an increasing alpha, whereas the Ni V lines indicated a decreasing alpha. Possible explanations for this could be misidentification of the lines, inaccurate atomic data, or wavelength dependent distortion in the spectrum. We examine the first two cases by using a high S/N reference spectrum from the hot sdO BD+28^{\circ}4211 to calibrate the Fe/Ni V atomic data. With this new data, we re-evaluate the work of Berengut et al. (2013) to derive a new constraint on the variation of alpha in a gravitational field.Comment: 4 pages, 2 figures: To appear in the proceedings of the "19th European White Dwarf Workshop" in Montreal, Canada, 201

    Lessons Learned

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    LLNL turned in 5 Declaration Line Items (DLI's) in 2006. Of these, one was declared completed. We made some changes to streamline our process from 2005, used less money, time and fewer team members. This report is a description of what changes we made in 2006 and what we learned. Many of our core review team had changed from last year, including our Laboratory Director, the Facility safety and security representatives, our Division Leader, and the OPSEC Committee Chair. We were able to hand out an AP Manual to some of them, and briefed all newcomers to the AP process. We first went to the OPSEC Committee and explained what the Additional Protocol process would be for 2006 and solicited their help in locating declarable projects. We utilized the 'three questions' from the AP meeting last year. LLNL has no single place to locate all projects at the laboratory. We talked to Resource Managers and key Managers in the Energy and Environment Directorate and in the Nonproliferation Homeland and International Security Directorate to find applicable projects. We also talked to the Principal Investigators who had projects last year. We reviewed a list of CRADA's and LDRD projects given to us by the Laboratory Site Office. Talking to the PI's proved difficult because of vacation or travel schedules. We were never able to locate one PI in town. Fortunately, collateral information allowed us to screen out his project. We had no problems in downloading new versions of the DWA and DDA. It was helpful for both Steve Blair and Arden Dougan to have write privileges. During the time we were working on the project, we had to tag-team the work to allow for travel and vacation schedules. We had some difficulty locating an 'activities block' in the software. This was mentioned as something we needed to fix from our 2005 declaration. Evidently the Activities Block has been removed from the current version of the software. We also had trouble finding the DLI Detail Report, which we included in our signature process last year. This report had been inadvertently omitted from the version of the software we used. We typed our own version of the Detail Report and the package was sent to signature. The final software was not available in time to include the DLI Report. We streamlined our review process for the Technical and Security Reviews by sending one letter to each entity instead of getting separate approvals from the subordinates, then getting an approval from the lead reviewer. The Review process took 20 days, far shorter than the 6 weeks it required last year. It will be difficult to shorten the process much more. One of our projects had associated laboratory work at NIF. This required many discussions with NIF management during the review process and before their paperwork came to them for signature since they were not aware of the Additional Protocol

    RocA truncation underpins hyper-encapsulation, carriage longevity and transmissibility of serotype M18 group A streptococci

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    Group A streptococcal isolates of serotype M18 are historically associated with epidemic waves of pharyngitis and the non-suppurative immune sequela rheumatic fever. The serotype is defined by a unique, highly encapsulated phenotype, yet the molecular basis for this unusual colony morphology is unknown. Here we identify a truncation in the regulatory protein RocA, unique to and conserved within our serotype M18 GAS collection, and demonstrate that it underlies the characteristic M18 capsule phenotype. Reciprocal allelic exchange mutagenesis of rocA between M18 GAS and M89 GAS demonstrated that truncation of RocA was both necessary and sufficient for hyper-encapsulation via up-regulation of both precursors required for hyaluronic acid synthesis. Although RocA was shown to positively enhance covR transcription, quantitative proteomics revealed RocA to be a metabolic regulator with activity beyond the CovR/S regulon. M18 GAS demonstrated a uniquely protuberant chain formation following culture on agar that was dependent on excess capsule and the RocA mutation. Correction of the M18 rocA mutation reduced GAS survival in human blood, and in vivo naso-pharyngeal carriage longevity in a murine model, with an associated drop in bacterial airborne transmission during infection. In summary, a naturally occurring truncation in a regulator explains the encapsulation phenotype, carriage longevity and transmissibility of M18 GAS, highlighting the close interrelation of metabolism, capsule and virulence

    Antimicrobial resistance in human populations: challenges and opportunities.

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    Antimicrobial resistance (AMR) is a global public health threat. Emergence of AMR occurs naturally, but can also be selected for by antimicrobial exposure in clinical and veterinary medicine. Despite growing worldwide attention to AMR, there are substantial limitations in our understanding of the burden, distribution and determinants of AMR at the population level. We highlight the importance of population-based approaches to assess the association between antimicrobial use and AMR in humans and animals. Such approaches are needed to improve our understanding of the development and spread of AMR in order to inform strategies for the prevention, detection and management of AMR, and to support the sustainable use of antimicrobials in healthcare

    Black Hole Interaction Energy

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    The interaction energy between two black holes at large separation distance is calculated. The first term in the expansion corresponds to the Newtonian interaction between the masses. The second term corresponds to the spin-spin interaction. The calculation is based on the interaction energy defined on the two black holes initial data. No test particle approximation is used. The relation between this formula and cosmic censorship is discussed.Comment: 18 pages, 2 figures, LaTeX2

    Angular momentum and an invariant quasilocal energy in general relativity

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    Owing to its transformation property under local boosts, the Brown-York quasilocal energy surface density is the analogue of E in the special relativity formula: E^2-p^2=m^2. In this paper I will motivate the general relativistic version of this formula, and thereby arrive at a geometrically natural definition of an `invariant quasilocal energy', or IQE. In analogy with the invariant mass m, the IQE is invariant under local boosts of the set of observers on a given two-surface S in spacetime. A reference energy subtraction procedure is required, but in contrast to the Brown-York procedure, S is isometrically embedded into a four-dimensional reference spacetime. This virtually eliminates the embeddability problem inherent in the use of a three-dimensional reference space, but introduces a new one: such embeddings are not unique, leading to an ambiguity in the reference IQE. However, in this codimension-two setting there are two curvatures associated with S: the curvatures of its tangent and normal bundles. Taking advantage of this fact, I will suggest a possible way to resolve the embedding ambiguity, which at the same time will be seen to incorporate angular momentum into the energy at the quasilocal level. I will analyze the IQE in the following cases: both the spatial and future null infinity limits of a large sphere in asymptotically flat spacetimes; a small sphere shrinking toward a point along either spatial or null directions; and finally, in asymptotically anti-de Sitter spacetimes. The last case reveals a striking similarity between the reference IQE and a certain counterterm energy recently proposed in the context of the conjectured AdS/CFT correspondence.Comment: 54 pages LaTeX, no figures, includes brief summary of results, submitted to Physical Review

    Post-vaccine epidemiology of serotype 3 pneumococci identifies transformation inhibition through prophage-driven alteration of a non-coding RNA

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    Background: The respiratory pathogen Streptococcus pneumoniae (the pneumococcus) is a genetically diverse bacterium associated with over 101 immunologically distinct polysaccharide capsules (serotypes). Polysaccharide conjugate vaccines (PCVs) have successfully eliminated multiple targeted serotypes, yet the mucoid serotype 3 has persisted despite its inclusion in PCV13. This capsule type is predominantly associated with a single globally disseminated strain, GPSC12 (clonal complex 180).Methods: A genomic epidemiology study combined previous surveillance datasets of serotype 3 pneumococci to analyse the population structure, dynamics, and differences in rates of diversification within GPSC12 during the period of PCV introductions. Transcriptomic analyses, whole genome sequencing, mutagenesis, and electron microscopy were used to characterise the phenotypic impact of loci hypothesised to affect this strain's evolution.Results: GPSC12 was split into clades by a genomic analysis. Clade I, the most common, rarely underwent transformation, but was typically infected with the prophage phi OXC141. Prior to the introduction of PCV13, this Glade's composition shifted towards a phi OXC141-negative subpopulation in a systematically sampled UK collection. In the post-PCV13 era, more rapidly recombining non-Clade I isolates, also phi OXC141-negative, have risen in prevalence. The low in vitro transformation efficiency of a Clade I isolate could not be fully explained by the similar to 100-fold reduction attributable to the serotype 3 capsule. Accordingly, prophage phi OXC141 was found to modify csRNA3, a non-coding RNA that inhibits the induction of transformation. This alteration was identified in -30% of all pneumococci and was particularly common in the unusually clonal serotype 1 GPSC2 strain. RNA-seq and quantitative reverse transcriptase PCR experiments using a genetically tractable pneumococcus demonstrated the altered csRNA3 was more effective at inhibiting production of the competence-stimulating peptide pheromone. This resulted in a reduction in the induction of competence for transformation.Conclusion: This interference with the quorum sensing needed to induce competence reduces the risk of the prophage being deleted by homologous recombination. Hence the selfish prophage-driven alteration of a regulatory RNA limits cell-cell communication and horizontal gene transfer, complicating the interpretation of post-vaccine population dynamics
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