645 research outputs found

    Some natural zero one laws for ordinals below ε0

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    We are going to prove that every ordinal α with ε_0 > α ≥ ω^ω satisfies a natural zero one law in the following sense. For α < ε_0 let Nα be the number of occurences of ω in the Cantor normal form of α. (Nα is then the number of edges in the unordered tree which can canonically be associated with α.) We prove that for any α with ω ω  ≤ α < ε_0 and any sentence ϕ in the language of linear orders the asymptotic density of ϕ along α is an element of  {0,1}. We further show that for any such sentence ϕ the asymptotic density along ε_0 exists although this limit is in general in between 0 and 1. We also investigate corresponding asymptotic densities for ordinals below ω^ω

    Canola seed as affected by swathing time

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    Non-Peer ReviewedYield, weight, protein content (oil-free meal) and oil content of canola seed increased as seeds developed. Maximum values were obtained between 45-49 days after flowering, when seed moisture was 29-38%. Fatty acid composition of canola seed oil changed during seed development. The proportion of oleic (C18:1) and linolenic (C18:3) acids increased, while that of most other fatty acids decreased, as seeds developed, while Eicosenoic (C20:1) and erucic (C22:1) acids did not show a clear trend. Fatty-acids tended to stabilize by the 49th day after flowering. Early seeding resulted in higher seed yield, larger seeds, lower seed protein content and higher seed oil content, when compared to late seeding

    National geological screening : East Anglia region

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    This report is the published product of one of a series of studies covering England, Wales and Northern Ireland commissioned by Radioactive Waste Management (RWM) Ltd. The report provides geological information about the East Anglia region to underpin the process of national geological screening set out in the UK’s government White Paper Implementing geological disposal: a framework for the long-term management of higher activity radioactive waste (DECC, 2014). The report describes geological features relevant to the safety requirements of a geological disposal facility (GDF) for radioactive waste emplaced onshore and up to 20 km offshore at depths between 200 and 1000 m from surface. It is written for a technical audience but is intended to inform RWM in its discussions with communities interested in finding out about the potential for their area to host a GDF

    The Anatomy of a Magnetar: XMM Monitoring of the Transient Anomalous X-ray Pulsar XTE J1810-197

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    We present the latest results from a multi-epoch timing and spectral study of the Transient Anomalous X-ray Pulsar XTE J1810-197. We have acquired seven observations of this pulsar with the Newton X-ray Multi-mirror Mission (XMM-Newton) over the course of two and a half years, to follow the spectral evolution as the source fades from outburst. The spectrum is arguably best characterized by a two-temperature blackbody whose luminosities are decreasing exponentially with tau_1 = 870 days and tau_2 = 280 days, respectively. The temperatures of these components are currently cooling at a rate of 22% per year from a nearly constant value recorded at earlier epochs of kT_1 = 0.25 keV and kT_2 = 0.67 keV, respectively. The new data show that the temperature T_1 and luminosity of that component have nearly returned to their historic quiescent levels and that its pulsed fraction, which has steadily decreased with time, is now consistent with the previous lack of detected pulsations in quiescence. We also summarize the detections of radio emission from XTE J1810-197, the first confirmed for any AXP. We consider possible models for the emission geometry and mechanisms of XTE J1810-197.Comment: 8 pages, 7 figures, 1 table, latex. To appear in the proceedings of "Isolated Neutron Stars", Astrophysics & Space Science, in pres

    Recent Progress on Anomalous X-ray Pulsars

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    I review recent observational progress on Anomalous X-ray Pulsars, with an emphasis on timing, variability, and spectra. Highlighted results include the recent timing and flux stabilization of the notoriously unstable AXP 1E 1048.1-5937, the remarkable glitches seen in two AXPs, the newly recognized variety of AXP variability types, including outbursts, bursts, flares, and pulse profile changes, as well as recent discoveries regarding AXP spectra, including their surprising hard X-ray and far-infrared emission, as well as the pulsed radio emission seen in one source. Much has been learned about these enigmatic objects over the past few years, with the pace of discoveries remaining steady. However additional work on both observational and theoretical fronts is needed before we have a comprehensive understanding of AXPs and their place in the zoo of manifestations of young neutron stars.Comment: 10 pages, 6 figures; to appear in proceedings of the conference "Isolated Neutron Stars: From the Interior to the Surface" eds. S. Zane, R. Turolla, D. Page; Astrophysics & Space Science in pres

    Theory of nuclear induced spectral diffusion: Spin decoherence of phosphorus donors in Si and GaAs quantum dots

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    We propose a model for spectral diffusion of localized spins in semiconductors due to the dipolar fluctuations of lattice nuclear spins. Each nuclear spin flip-flop is assumed to be independent, the rate for this process being calculated by a method of moments. Our calculated spin decoherence time TM=0.64T_{M}=0.64 ms for donor electron spins in Si:P is a factor of two longer than spin echo decay measurements. For 31^{31}P nuclear spins we show that spectral diffusion is well into the motional narrowing regime. The calculation for GaAs quantum dots gives TM=10−50T_{M}=10-50 μ\mus depending on the quantum dot size. Our theory indicates that nuclear induced spectral diffusion should not be a serious problem in developing spin-based semiconductor quantum computer architectures.Comment: 15 pages, 9 figures. Accepted for publication in Phys. Rev.

    Modeling pulmonary alveolar microlithiasis by epithelial deletion of the Npt2b sodium phosphate cotransporter reveals putative biomarkers and strategies for treatment

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    Pulmonary alveolar microlithiasis (PAM) is a rare, autosomal recessive lung disorder associated with progressive accumulation of calcium phosphate microliths. Inactivating mutations in SLC34A2, which encodes the NPT2b sodiumdependent phosphate cotransporter, has been proposed as a cause of PAM.Weshow that epithelial deletion ofNpt2b in mice results in a progressive pulmonary process characterized by diffuse alveolar microlith accumulation, radiographic opacification, restrictive physiology, inflammation, fibrosis, and an unexpected alveolar phospholipidosis. Cytokine and surfactant protein elevations in the alveolar lavage and serum of PAM mice and confirmed in serum from PAM patients identify serum MCP-1 (monocyte chemotactic protein 1) and SP-D (surfactant protein D) as potential biomarkers.Microliths introduced by adoptive transfer into the lungs of wild-typemice produce markedmacrophagerich inflammation and elevation of serum MCP-1 that peaks at 1 week and resolves at 1 month, concomitant with clearance of stones. Microliths isolated by bronchoalveolar lavage readily dissolve in EDTA, and therapeutic wholelung EDTA lavage reduces the burden of stones in the lungs. A low-phosphate diet prevents microlith formation in young animals and reduces lung injury on the basis of reduction in serum SP-D. The burden of pulmonary calcium deposits in established PAM is also diminished within 4 weeks by a low-phosphate diet challenge. These data support a causative role for Npt2b in the pathogenesis of PAM and the use of the PAMmouse model as a preclinical platform for the development of biomarkers and therapeutic strategies

    The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays

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    For the first time a quasi-simultaneous multi-wavelength campaign has been performed on an Anomalous X-ray Pulsar from the radio to the hard X-ray band. 4U 0142+61 was an INTEGRAL target for 1 Ms in July 2005. During these observations it was also observed in the X-ray band with Swift and RXTE, in the optical and NIR with Gemini North and in the radio with the WSRT. In this paper we present the source-energy distribution. The spectral results obtained in the individual wave bands do not connect smoothly; apparently components of different origin contribute to the total spectrum. Remarkable is that the INTEGRAL hard X-ray spectrum (power-law index 0.79 +/- 0.10) is now measured up to an energy of ~230 keV with no indication of a spectral break. Extrapolation of the INTEGRAL power-law spectrum to lower energies passes orders of magnitude underneath the NIR and optical fluxes, as well as the low ~30 microJy (2 sigma) upper limit in the radio band.Comment: 6 pages, 1 figure. To be published in the proceedings of the conference "Isolated Neutron Stars: from the Interior to the Surface" (April 24-28, 2006, London, UK), eds. S. Zane, R. Turolla and D. Pag
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