Evidence for polar jets as precursors of polar plume formation

Observations from the Hinode/XRT telescope and STEREO/SECCHI/EUVI are utilized to study polar coronal jets and plumes. The study focuses on the temporal evolution of both structures and their relationship. The data sample, spanning April 7-8 2007, shows that over 90% of the 28 observed jet events are associated with polar plumes. EUV images (STEREO/SECCHI) show plume haze rising from the location of approximately 70% of the polar X-ray (Hinode/XRT) and EUV jets, with the plume haze appearing minutes to hours after the jet was observed. The remaining jets occurred in areas where plume material previously existed causing a brightness enhancement of the latter after the jet event. Short-lived, jet-like events and small transient bright points are seen (one at a time) at different locations within the base of pre-existing long-lived plumes. X-ray images also show instances (at least two events) of collimated-thin jets rapidly evolving into significantly wider plume-like structures that are followed by the delayed appearance of plume haze in the EUV. These observations provide evidence that X-ray jets are precursors of polar plumes, and in some cases cause brightenings of plumes. Possible mechanisms to explain the observed jet and plume relationship are discussed.Comment: 10 pages, 4 figures, accepted as APJ Lette

The decline in irradiation from the white dwarf in old novae

Aims: We have investigated how a flux ratio analysis of the light curves of cataclysmic variables can be used to calculate the luminosity irradiating the secondary star in the classical novae QU Vul, V Per, DD Cir, DN Gem, V1432 Aql , and WY Sge. Methods: We undertook phase-resolved, near-infrared K band photometry of QU Vul and V Per. Using data from QU Vul we show how flux ratios taken between fiducial orbital phases in the light curves of irradiated CVs can be used to measure the degree of heating of the secondary star. We compared the heating effect obtained from flux ratio analysis with more formal modelling, or by measurements taken from the literature, and found good agreement. We used the results to determine how irradiation changes with time since the nova outburst. Results: The light curve of QU Vul shows the presence of two maxima in the K band, which are displaced from phase 0.25 towards the 0.5 phase position, as would be expected from heating of the inner face of the secondary star by radiation from hot primary. Nova V Per, on the other hand shows evidence for a hot spot on the accretion disc, and it would appear that heating of the inner face is not occurring. The results of the flux ratio analysis of the objects examined are plotted as a function of time since the nova explosions occurred. There is marginal evidence for a decline in flux with time since the outburst, superimposed on considerable scatter, which is likely to be caused by the different temperature reached in each nova explosion. The decline is consistent with the declines others have seen. We conclude that it is the decline in reprocessed irradiation from the cooling white dwarf alone, rather than a decline in mass transfer rate, that could be the cause of the decrease in optical brightness seen in old novae

Taxonomic informatics tools for the electronic nomenclator zoologicus

Author Posting. © Marine Biological Laboratory , 2006. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 210 (2006): 18-24.Given the current trends, it seems inevitable that all biological documents will eventually exist in a digital format and be distributed across the internet. New network services and tools need to be developed to increase retrieval rates for documents and to refine data recovery. Biological data have traditionally been well managed using taxonomic principles. As part of a larger initiative to build an array of names-based network services that emulate taxonomic principles for managing biological information, we undertook the digitization of a major taxonomic reference text, Nomenclator Zoologicus. The process involved replicating the text to a high level of fidelity, parsing the content for inclusion within a database, developing tools to enable expert input into the product, and integrating the metadata and factual content within taxonomic network services. The result is a high-quality and freely available web application (http://uio.mbl.edu/NomenclatorZoologicus/) capable of being exploited in an array of biological informatics services.This work was supported with funding from the Andrew W. Mellon Foundation and GBIF

An interstellar precursor mission

A mission out of the planetary system, with launch about the year 2000, could provide valuable scientific data as well as test some of the technology for a later mission to another star. Primary scientific objectives for the precursor mission concern characteristics of the heliopause, the interstellar medium, stellar distances (by parallax measurements), low energy cosmic rays, interplanetary gas distribution, and mass of the solar system. Secondary objectives include investigation of Pluto. Candidate science instruments are suggested. Individual spacecraft systems for the mission were considered, technology requirements and problem areas noted, and a number of recommendations made for technology study and advanced development. The most critical technology needs include attainment of 50-yr spacecraft lifetime and development of a long-life NEP system

Does the association of prostate cancer with night-shift work differ according to rotating vs. fixed schedule? A systematic review and meta-analysis

Background: Recent studies suggested that the relation between night-shift work and prostate cancer may differ between rotating and fixed schedules. Objectives: We aimed to quantify the independent association between night-shift work and prostate cancer, for rotating and fixed schedules. Methods: We searched MEDLINE for studies assessing the association of night-shift work, by rotating or fixed schedules, with prostate cancer. We computed summary relative risk (RR) estimates with 95% confidence intervals (95% CI) using the inverse variance method and quantified heterogeneity using the I2 statistic. Meta-regression analysis was used to compare the summary RR estimates for rotating and fixed schedules, while reducing heterogeneity. Results: A total of nine studies assessed the effect of rotating and, in addition, four of them provided the effect of fixed night-shift work, in relation to daytime workers. Rotating night-shift work was associated with a significantly increased risk of prostate cancer (RR = 1.06, 95% CI of 1.01 to 1.12; I2 = 50%), but not fixed night-shift work (RR of 1.01, 95% CI of 0.81 to 1.26; I2 = 33%). In meta-regression model including study design, type of population, and control of confounding, the summary RR was 20% higher for rotating vs. fixed schedule, with heterogeneity fully explained by these variables. Conclusions: This is the first meta-analysis suggesting that an increased risk of prostate cancer may be restricted to workers with rotating night shifts. However, the association was weak and additional studies are needed to further clarify this relation before it can be translated into measures for risk reduction in occupational settings

Short-Distance Structure of Nuclei

One of Jefferson Lab's original missions was to further our understanding of the short-distance structure of nuclei. In particular, to understand what happens when two or more nucleons within a nucleus have strongly overlapping wave-functions; a phenomena commonly referred to as short-range correlations. Herein, we review the results of the (e,e'), (e,e'p) and (e,e'pN) reactions that have been used at Jefferson Lab to probe this short-distance structure as well as provide an outlook for future experiments.Comment: 16 pages, 8 figures, for publication in Journal of Physics

A more representative chamber: representation and the House of Lords

Since 1997 there has been substantive reform of the House of Lords in an effort to make the chamber ‘more democratic and more representative’. Whilst the Labour government failed to press ahead with any of the proposed plans for further reform following the removal of the bulk of the hereditary peers in 1999, it remained committed to the notion that such reform must make the second chamber ‘more representative’. The coalition government's programme advocates a long-term aspiration for a House wholly or mainly elected on the basis of proportional representation, and a short-term approach based on additional appointments to ensure a balance of the parties. What is clear in all of these proposals for reform is a desire for the House of Lords to become more representative than it is at present. However, what is less clear is what is meant by ‘representative’ – who the House of Lords is supposed to represent, and what form representation will take. Moreover, in proposing to make the chamber more representative, either through appointment or election, little attention has been paid to how the current House of Lords provides representation. This article examines these questions in the context of Pitkin's classic conceptions of representation and peers' attitudes towards their own representative rol

Little boxes: A simple implementation of the Greenberger, Horne, and Zeilinger result for spatial degrees of freedom

A Greenberger, Horne, and Zeilinger-type construction is realized in the position properties of three particles whose wavefunctions are distributed over three two-chambered boxes. The same system is modeled more realistically using three spatially separated, singly ionized hydrogen molecules. © 2011 American Association of Physics Teachers

The majority of re-activatable latent HIV proviruses are genetically distinct with no evidence of ongoing evolution

Background Two mechanisms have been proposed to contribute in to the maintenance of the HIV latent reservoir: homeostatic proliferation of latently infected cells and low level viral replication in the lymphoid tissue. Here we studied the sequences of reactivatable latent viruses obtained from a stably treated patient to assess the importance of these mechanisms. Methods Resting CD4+ T cells were isolated at regular intervals from the patient, underwent limiting dilution, were activated and then co-cultured with SupT1-CCR5 cells for 21 days. The supernatant was harvested for viral RNA. Regions in gag and env were analysed by Sanger sequencing. To control for artefacts from culture and sequencing, SupT1-CCR5 cells were infected with NL4-3 and underwent the same limiting dilution, culture, and sequencing processes. Pairwise comparisons were performed to obtain p-distances. Each pair of patient derived viral sequences was considered distinct if the p-distance was higher than that of the corresponding region of the sequences from NL4-3 infected SupT1-CCR5 cells. To seek evidence of viral evolution, a consensus was created from the viral sequences obtained from the first sample and sequences from samples obtained subsequently were compared against this baseline consensus. Results We obtained 32 sequences of reactivated latent viruses from a single patient. 18 distinct sequences could be distinguished from the gag region. The remaining 14 sequences segregated into five groups. However, when the env regions of these 14 sequences were analysed, only one ‘clonal’ group of two sequences remained. 30/32 reactivated latent viruses were distinct. If the threshold p-distance for two sequences to be considered distinct was set at the maximal (rather than average) p-distance observed in the reference set, 26/32 of reactivated latent viruses would still be considered distinct. We have not observed any increase in p-distances over 28 weeks of sampling compared to the baseline samples to suggest of accumulation of mutations. Conclusion Our results show that the majority of reactivatable latent viruses are genetically distinct. Persistent viral evolution was not observed in the latent reservoir harboured in peripheral blood resting CD4+ T cells in this stably treated patient

Linearized solutions of the Einstein equations within a Bondi-Sachs framework, and implications for boundary conditions in numerical simulations

We linearize the Einstein equations when the metric is Bondi-Sachs, when the background is Schwarzschild or Minkowski, and when there is a matter source in the form of a thin shell whose density varies with time and angular position. By performing an eigenfunction decomposition, we reduce the problem to a system of linear ordinary differential equations which we are able to solve. The solutions are relevant to the characteristic formulation of numerical relativity: (a) as exact solutions against which computations of gravitational radiation can be compared; and (b) in formulating boundary conditions on the $r=2M$ Schwarzschild horizon.Comment: Revised following referee comment