A second-order artificial satellite theory based on an intermediate orbit

Second order artificial satellite theory based on intermediate orbi

Orbit improvement of the satellites of the outer planets

Data reduced from 127 plates showing Jupiter's and Saturn's satellites in the interval 1972 to 1974 are available on computer cards in the form of (O-C) residuals. Initial orbit calculations and several later orbit improvements for Jupiter XIII (Leda) culminated in an extended ephemeris for Leda to the year 2000. The possible existence of several small satellites just outside Saturns rings was predicted. De Sitter's incomplete theory for the motion of the Galilean satellites was reviewed and an outline for a revised, complete theory was developed. Observations of nearly 100 relative positions of the Galilean satellite with a mean accuracy of about 100 km (0.03 arc sec) were used to improve Sampson's theory for these satellites. Results were published on (1) a long term upper limit to Jupiter's orbital eccentricity; (2) deviation of an accurate modern value of the ellipticity of Uranus from balloon-borne images and consequent evaluation of the planet's rotation rate; and (3) identification of features in Saturn's rings as produced by heretofore undetected tesseral harmonics of Saturn's gravitational field

Mitigation of oxygen decline in fjords by freshwater injection

The exchange of water masses between deep fjords and the open ocean is commonly constrained by a topographical barrier called the sill. While fjord water above the sill depth communicates relatively freely with the open ocean, water below the sill depth is caught inside the fjord basin. This basin water may remain stagnant in deep fjords for many successive years. During these periods, the biological consumption of dissolved oxygen is larger than the supply of new oxygen, and the fjord basin might experience hypoxia and even anoxia. Such deoxygenation is natural but can be amplified by warming and human activities involving supplies of organic matter and other nutrients. Here, we use a general circulation model to explore how deoxygenation can be mitigated by injecting fresh water into the fjord basin. The freshwater injection causes density reduction of the basin water with subsequent water exchange and oxygenation. Our results suggest that the basin water of Masfjorden, a 480 m deep fjord with a basin volume of 4 × 109 m3, can avoid deoxygenation with a continuous freshwater injection of 0.05 m3 s−1. We conclude that freshwater injection might be an efficient tool to mitigate the deoxygenation of fjord basins.publishedVersio

An experimental model for the study of long-term parenteral nutrition in pig. Morbidity, microbiological and biochemical findings

We have established an animal model for studies of total parenteral nutrition (TPN) regimen. Pigs were given long-term lipid based TPN after a formula recommended to children. Central venous catheter colonization rate was not significantlyraised in entirely parenterally fed animals. In the same animals, intestinal microflora-associated characteristics and light microscopic evaluation of the intestinal mucosa indicated a quantitative intact mieroflora and absence of mucosal atrophy.Still morbidity was significantly higher in entirely parenterally fed animals given the same caloric load as enterally ted. Since there was a dietary substance (lat, protein and carbohydrate) unbalance, however, it is impossible to conclude whetherthe TPN was insufficient or had adverse efleets. The model will permit further investigtion of such TPN effects

A phase IIa, nonrandomized study of radium-223 dichloride in advanced breast cancer patients with bone-dominant disease

Radium-223 dichloride (radium-223) mimics calcium and emits high-energy, short-range alpha-particles resulting in an antitumor effect on bone metastases. This open-label, phase IIa nonrandomized study investigated safety and short-term efficacy of radium-223 in breast cancer patients with bone-dominant disease. Twenty-three advanced breast cancer patients with progressive bone-dominant disease, and no longer candidates for further endocrine therapy, were to receive radium-223 (50 kBq/kg IV) every 4 weeks for 4 cycles. The coprimary end points were change in urinary N-telopeptide of type 1 (uNTX-1) and serum bone alkaline phosphatase (bALP) after 16 weeks of treatment. Exploratory end points included sequential 18F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) to assess metabolic changes in osteoblastic bone metastases. Safety data were collected for all patients. Radium-223 significantly reduced uNTX-1 and bALP from baseline to end of treatment. Median uNTX-1 change was −10.1 nmol bone collagen equivalents/mmol creatinine (−32.8 %; P = 0.0124); median bALP change was −16.7 ng/mL (−42.0 %; P = 0.0045). Twenty of twenty-three patients had FDG PET/CT identifying 155 hypermetabolic osteoblastic bone lesions at baseline: 50 lesions showed metabolic decrease (≥25 % reduction of maximum standardized uptake value from baseline) after 2 radium-223 injections [32.3 % metabolic response rate (mRR) at week 9], persisting after the treatment period (41.5 % mRR at week 17). Radium-223 was safe and well tolerated. Radium-223 targets areas of increased bone metabolism and shows biological activity in advanced breast cancer patients with bone-dominant disease

Observational detection of eight mutual eclipses and occultations between the satellites of Uranus

We carried out observations, with five different instruments ranging in aperture from 0.4m to 10m, of the satellites of Uranus during that planet's 2007 Equinox. Our observations covered specific intervals of time when mutual eclipses and occultations were predicted. The observations were carried out in the near-infrared part of the spectrum to mitigate the glare from the planet. Frames were acquired at rates > 1/min. Following modelling and subtraction of the planetary source from these frames, differential aperture photometry was carried out on the satellite pairs involved in the predicted events. In all cases but one, nearby bright satellites were used as reference sources. We have obtained fifteen individual lightcurves, eight of which show a clear drop in the flux from the satellite pair, indicating that a mutual event took place. Three of these involve the faint satellite Miranda. All eight lightcurves were model-fitted to yield best estimates of the time of maximum flux drop and the impact parameter. In three cases best-fit albedo ratios were also derived. We used these estimates to generate intersatellite astrometric positions with typical formal uncertainties of <0.01 arcsec, several times better than conventional astrometry of these satellites. The statistics of our estimated event midtimes show a systematic lag, with the observations later than predictions. In addition, lightcurves of two partial eclipses of Miranda show no statistically significant evidence of a light drop, at variance with the predictions. These indicate that new information about the Uranian satellite system is contained in observations of mutual events acquired here and by other groups.Comment: 8 pages, 3 figures, accepted for publication in Astronomy and Astrophysics Uses aa style packag

The role of chaotic resonances in the solar system

Our understanding of the Solar System has been revolutionized over the past decade by the finding that the orbits of the planets are inherently chaotic. In extreme cases, chaotic motions can change the relative positions of the planets around stars, and even eject a planet from a system. Moreover, the spin axis of a planet-Earth's spin axis regulates our seasons-may evolve chaotically, with adverse effects on the climates of otherwise biologically interesting planets. Some of the recently discovered extrasolar planetary systems contain multiple planets, and it is likely that some of these are chaotic as well.Comment: 28 pages, 9 figure

Author Self-Citation in the General Medicine Literature

Background: Author self-citation contributes to the overall citation count of an article and the impact factor of the journal in which it appears. Little is known, however, about the extent of self-citation in the general clinical medicine literature. The objective of this study was to determine the extent and temporal pattern of author self-citation and the article characteristics associated with author self-citation. Methodology/Principal Findings: We performed a retrospective cohort study of articles published in three high impact general medical journals (JAMA, Lancet, and New England Journal of Medicine) between October 1, 1999 and March 31, 2000. We retrieved the number and percentage of author self-citations received by the article since publication, as of June 2008, from the Scopus citation database. Several article characteristics were extracted by two blinded, independent reviewers for each article in the cohort and analyzed in multivariable linear regression analyses. Since publication, author self-citations accounted for 6.5 % (95 % confidence interval 6.3–6.7%) of all citations received by the 328 articles in our sample. Selfcitation peaked in 2002, declining annually thereafter. Studies with more authors, in cardiovascular medicine or infectious disease, and with smaller sample size were associated with more author self-citations and higher percentage of author selfcitation (all p#0.01). Conclusions/Significance: Approximately 1 in 15 citations of articles in high-profile general medicine journals are autho