Convergence rates of the DPG method with reduced test space degree

This paper presents a duality theorem of the Aubin-Nitsche type for discontinuous Petrov Galerkin (DPG) methods. This explains the numerically observed higher convergence rates in weaker norms. Considering the specific example of the mild-weak (or primal) DPG method for the Laplace equation, two further results are obtained. First, the DPG method continues to be solvable even when the test space degree is reduced, provided it is odd. Second, a non-conforming method of analysis is developed to explain the numerically observed convergence rates for a test space of reduced degree

Spatial Distribution of Metal Emissions in SNR 3C 397 Viewed with Chandra and XMM

We present X-ray equivalent width imaging of the supernova remnant (SNR) 3C 397 for Mg He\alpha, Si He\alpha, S He\alpha, and Fe K\alpha complex lines with the Chandra and XMM-Newton observations. The images reveal that the heavier the element is, the smaller the extent of the element distribution is. The Mg emission is evidently enhanced in the southeastern blow-out region, well along the radio boundary there, and appears to partially envelope the eastern Fe knot. Two bilateral hat-like Si line-emitting structures are along the northern and southern borders, roughly symmetric with respect to the southeast-northwest elongation axis. An S line-emitting shell is located just inner to the northern radio and IR shell, indicating of a layer of reversely shocked sulphur in the ejecta. A few enhanced Fe features are basically aligned along the diagonal of the rectangular shape of the SNR, which implicates an early asymmetric SN explosion.Comment: 4 pages, 4 figures, appears in Science China Physics, Mechanics & Astronomy, 2010, 53 (Suppl.1), 267-27

The Connection between Supernova Remnants and the Galactic Magnetic Field: A Global Radio Study of the Axisymmetric Sample

The study of supernova remnants (SNRs) is fundamental to understanding the chemical enrichment and magnetism in galaxies, including our own Milky Way. In an effort to understand the connection between the morphology of SNRs and the Galactic magnetic field (GMF), we have examined the radio images of all known SNRs in our Galaxy and compiled a large sample that have an "axisymmetric" morphology, which we define to mean SNRs with a "bilateral" or "barrel"-shaped morphology, in addition to one-sided shells. We selected the cleanest examples and model each of these at their appropriate Galactic position using two GMF models, those of Jansson & Farrar (2012a), which includes a vertical halo component, and Sun et al. (2008) that is oriented entirely parallel to the plane. Since the magnitude and relative orientation of the magnetic field changes with distance from the sun, we analyse a range of distances, from 0.5 to 10 kpc in each case. Using a physically motivated model of a SNR expanding into the ambient GMF, we find the models using Jansson & Farrar (2012a) are able to reproduce observed morphologies of many SNRs in our sample. These results strongly support the presence of an off-plane, vertical component to the GMF, and the importance of the Galactic field on SNR morphology. Our approach also provides a potential new method for determining distances to SNRs, or conversely, distances to features in the large-scale GMF if SNR distances are known.Comment: 24 pages, 8 figures plus one 5-page appendix figure, 3 tables, accepted to A&

Multiplexed communication over a high-speed quantum channel

In quantum information systems it is of particular interest to consider the best way in which to use the non-classical resources consumed by that system. Quantum communication protocols are integral to quantum information systems and are amongst the most promising near-term applications of quantum information science. Here we show that a multiplexed, digital quantum communications system supported by comb of vacuum squeezing has a greater channel capacity per photon than a source of broadband squeezing with the same analogue bandwidth. We report on the time-resolved, simultaneous observation of the first dozen teeth in a 2.4 GHz comb of vacuum squeezing produced by a sub-threshold OPO, as required for such a quantum communications channel. We also demonstrate multiplexed communication on that channel

Quality and biochemical changes of sweet cherries cv. Regina stored in modified atmosphere packaging

Biochemical and quality changes of sweet cherries cv. Regina were assessed over three consecutive years after storage in different modified atmosphere packaging (MAP) liners, with or without hydrocooling, compared to regular atmosphere (RA) storage. All plastic liners used in the experiment resulted in CO2-enrichment and O2-reduction inside packages, with the following impact on fruit quality after five weeks of storage: improved retention of fruit firmness and red color of skin, no significant effect on acidity and total soluble solids, and minimal loss of fruit weight. Fruit decay was absent under both storage conditions (RA and MAP), probably due to rain-protected cultivation of cherry trees. Stalks of MAP-fruits remained fresher than control fruits, obviously due to higher relative humidity condition inside packages. MA-packaged cherries were preferred by the taste panel, while cold-stored fruits were criticized due to flat and slightly bitter taste. The ATP concentration in air stored fruits was higher than in MA-packaged fruits, while ADP level was higher in MA-packaged fruits. Further, MA-packed sweet cherries exhibited higher antioxidant potential and ascorbic acid content than air-stored fruits. Moreover, hydrocooling did not cause any significant effect compared to nontreated fruits

Chandra Confirmation of a Pulsar Wind Nebula in DA 495

As part of a multiwavelength study of the unusual radio supernova remnant DA 495, we present observations made with the Chandra X-ray Observatory. Imaging and spectroscopic analysis confirms the previously detected X-ray source at the heart of the annular radio nebula, establishing the radiative properties of two key emission components: a soft unresolved source with a blackbody temperature of 1 MK consistent with a neutron star, surrounded by a nonthermal nebula 40'' in diameter exhibiting a power-law spectrum with photon index Gamma = 1.6+/-0.3, typical of a pulsar wind nebula. The implied spin-down luminosity of the neutron star, assuming a conversion efficiency to nebular flux appropriate to Vela-like pulsars, is ~10^{35} ergs/s, again typical of objects a few tens of kyr old. Morphologically, the nebular flux is slightly enhanced along a direction, in projection on the sky, independently demonstrated to be of significance in radio polarization observations; we argue that this represents the orientation of the pulsar spin axis. At smaller scales, a narrow X-ray feature is seen extending out 5'' from the point source, a distance consistent with the sizes of resolved wind termination shocks around many Vela-like pulsars. Finally, we argue based on synchrotron lifetimes in the estimated nebular magnetic field that DA 495 represents a rare pulsar wind nebula in which electromagnetic flux makes up a significant part, together with particle flux, of the neutron star's wind, and that this high magnetization factor may account for the nebula's low luminosity.Comment: 26 pages, 5 figures, AASTeX preprint style. Accepted for publication in The Astrophysical Journa

Socioeconomic and demographic factors associated with failure in Helicobacter pylori eradication using the standard triple therapy

Aim: To evaluate the influence of socioeconomic and demographic factors on the eradication rate of H. pylori, using standard triple therapy Background: the efficacy of the standard triple therapy (STT) for H. pylori eradication has decreased with the rise of antibiotic resistance. Other factors could influence the eradication failure, although available results are conflicting. Methods: Retrospective study, including adults with H. pylori infection treated de novo with STT (proton pump inhibitor, amoxicillin and clarithromycin). Eradication success was assessed by 13C-urea breath test. Demographic and socioeconomics variables were evaluated and correlated with eradication treatment outcome. The confounder variables were controlled by logistic regression analysis. Results: Out of 902 patients with H. pylori diagnosis, 693 met inclusion criteria (average age 53 years; females 55.2%). Nonsignificant differences were observed in relation to economics income between rural and urban areas (p=0.316). The eradication rate of H. pylori was 71.1%: male 78.9% vs female 65.9%, urban area 73.4% vs rural area 64.1%. With reference to age, income and nationality, the eradication rates were similar in all groups. According to logistic regression analysis, females had almost twice more likelihood of eradication failure in relation to males (OR 1.92; 95%CI: 1.38-2.72); and rural residents had OR 1.55 (95%CI: 1.03- 2.33) for having eradication failure in contrast with urban population. Conclusion: Female gender and rural residence are factors associated with H. Pylori eradication failure with standard triple therapy