642 research outputs found

    Letter from C. S. Newhall to John Muir, 1902 Jan 6.

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    [letterhead]Fresno, Cali. Jan. 6, 1902.Mr. John MuirMartinez, Cal...Dear Sir,I thank you very sincerely for your telegram of the 4th to the Commission. In the campaign last fall, I refused to allow the officers under me to leave there legitimate work for political work, & declined a demand for campaign money. Also a supervisor who was a political friend of a Congressman was discharged for inefficiency, or worse. And there was a charge I cannot account for that I had antagonized the Water & [illegible] Association. Under the circumstances I thought it allowable to write & telegraph as I did to you & Wm. Thomas, & Warren Olney & Pres. Jordan. The [illegible] was more than I anticipated. Very sincerely yours,C. S. Newhall [illegible] Supt.I enclose 1.10 for the telegram.0292

    A users' guide for SEARCH and ITER

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    Computer program for calculating initial values of trajectory and iterative program for running multiple cases with varied parameter

    JPL Development Ephemeris number 96

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    The fourth issue of JPL Planetary Ephemerides, designated JPL Development Ephemeris No. 96 (DE96), is described. This ephemeris replaces a previous issue which has become obsolete since its release in 1969. Improvements in this issue include more recent and more accurate observational data, new types of data, better processing of the data, and refined equations of motion which more accurately describe the actual physics of the solar system. The descriptions in this report include these new features as well as the new export version of the ephemeris. The tapes and requisite software will be distributed through the NASA Computer Software Management and Information Center (COSMIC) at the University of Georgia

    On the Dynamical Stability of the Solar System

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    A long-term numerical integration of the classical Newtonian approximation to the planetary orbital motions of the full Solar System (sun + 8 planets), spanning 20 Gyr, was performed. The results showed no severe instability arising over this time interval. Subsequently, utilizing a bifurcation method described by Jacques Laskar, two numerical experiments were performed with the goal of determining dynamically allowed evolutions for the Solar System in which the planetary orbits become unstable. The experiments yielded one evolution in which Mercury falls onto the Sun at ~1.261Gyr from now, and another in which Mercury and Venus collide in ~862Myr. In the latter solution, as a result of Mercury's unstable behavior, Mars was ejected from the Solar System at ~822Myr. We have performed a number of numerical tests that confirm these results, and indicate that they are not numerical artifacts. Using synthetic secular perturbation theory, we find that Mercury is destabilized via an entrance into a linear secular resonance with Jupiter in which their corresponding eigenfrequencies experience extended periods of commensurability. The effects of general relativity on the dynamical stability are discussed. An application of the bifurcation method to the outer Solar System (Jupiter, Saturn, Uranus, and Neptune) showed no sign of instability during the course of 24Gyr of integrations, in keeping with an expected Uranian dynamical lifetime of 10^(18) years.Comment: 37 pages, 18 figures, accepted for publication in the Astrophysical Journa

    Space - Single Precision Cowell Trajectory Program

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    Single Precision Cowell Trajectory program - digital computer program for trajectory computatio

    SFPRO - Single Precision Cowell Trajectory Processor

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    Digital computer program for IBM 7094 computer to generate spacecraft tracking station calculation

    Chlamydia trachomatis infection and the risk of perinatal mortality in Hungary

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    Introduction: Chlamydial infections of the genital tract are thought to often lead to preterm birth, which is the most important perinatal problem in Hungary. Aim of study: A multicenter study was carried out to determine the prevalence of Chlamydia trachomatis infection, risk factors for the infection and to relate the infection to perinatal mortality, accounting for potential confounding effects. Methods: The nucleic acid hybridization method (PACE2 Gen-Probe) was applied for the examination of Chlamydia trachomatis. Logistic regression analysis was used to assess risk. Results: A total of 6156 pregnant women were examined for the occurrence of Chlamydia trachomatis. The observed overall rate of chlamydial infection was 5.9%. Young age (less than 24 years old) (OR and 95% CI:1.6 (1.3-2.0)), unmarried status (1.5 (1.2-1.9)) and the high unemployment rate (2.1 (1.6-2.7)) were statistically significant predictors of the infection. In logistic regression analysis, chlamydial infection (1.9 (1.1-3.3)). high unemployment rate (1.5 (1.2-2.2)) and low birth weight (1.7 (1.1-2.7) were significant predictors of perinatal mortality. Conclusions: Testing pregnant women for diseases that can be transmitted perinatally is an important part of obstetric cart. Screening for C. trachomatis of unmarried women under 24 years of age is suggested and need increased observation during labor

    Projectile-shape dependence of impact craters in loose granular media

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    We report on the penetration of cylindrical projectiles dropped from rest into a dry, noncohesive granular medium. The cylinder length, diameter, density, and tip shape are all explicitly varied. For deep penetrations, as compared to the cylinder diameter, the data collapse onto a single scaling law that varies as the 1/3 power of the total drop distance, the 1/2 power of cylinder length, and the 1/6 power of cylinder diameter. For shallow penetrations, the projectile shape plays a crucial role with sharper objects penetrating deeper.Comment: 3 pages, 3 figures; experimen

    Menelusuri Kebenaran Letusan Gunung Merapi 1006

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    Http://dx.doi.org/10.17014/ijog.vol1no4.20064Until now, the large eruption of Merapi in 1006 is believed to take place although the truth is still debatable. Previous investigation proposed that the ”pralaya” of the Ancient Mataram Kingdom in 928 Saka (1006) was due to a volcanic activity. Bemmelen also inferred that impact of the eruption had destroyed and covered the Mendut and Borobudur Temples and dammed the Progo River. However, if the “pralaya” was caused by Merapi eruption, why the deposit that correlates to the the eruption is not recognized. If so, the eruption that covered the temples should have been very large, and left deposits around Merapi and of course easy to find. Historically, the “pralaya“ mentioned in the Pucangan Inscription did not happen in 1006, but in 1016 or 1017. However the “pralaya“ was caused by the attack of King Wurawari, not by the Merapi eruption. According to the history of Merapi eruptions, 11 large eruptions have occurred since 3000 years ago. However, none of those fi t with 1006 eruption. Except the large eruption (VEI 3-4), that produced Selo tephra, dated 1112 ± 73 years BP (765-911)

    High-frequency side-scan sonar fish reconnaissance by autonomous underwater vehicles

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    Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of NRC Research Press for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences 74 (2017): 240-255, doi:10.1139/cjfas-2015-0301.A dichotomy between depth penetration and resolution as a function of sonar frequency, draw resolution, and beam spread challenges fish target classification from sonar. Moving high-frequency sources to depth using autonomous underwater vehicles (AUVs) mitigates this and also co-locates transducers with other AUV-mounted short-range sensors to allow a holistic approach to ecological surveys. This widely available tool with a pedigree for bottom mapping is not commonly applied to fish reconnaissance and requires the development of an interpretation of pelagic reflective features, revisitation of count methods, image-processing rather than wave-form recognition for automation, and an understanding of bias. In a series of AUV mission test cases, side-scan sonar (600 and 900 kHz) returns often resolved individual school members, spacing, size, behavior, and (infrequently) species from anatomical features and could be intuitively classified by ecologists — but also produced artifacts. Fish often followed the AUV and thus were videographed, but in doing so removed themselves from the sonar aperture. AUV-supported high-frequency side-scan holds particular promise for survey of scarce, large species or for synergistic investigation of predators and their prey because the spatial scale of observations may be similar to those of predators.AUV missions were funded by an Office of Naval Research grant to the Woods Hole Oceanographic Institution and Rutgers University. The field work was supported by the Office of Naval Research under grant N00014-11-1-0160
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