242 research outputs found

    The role of SLR and LLR in relativity

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    While General Relativity has been adopted as the standard theory of relativity, there are alternative theories, with important implications for gravitational physics, which can only be discounted with tests of sufficient accuracy. In addition to its contributions to lunar and solar system dynamics, Lunar Laser Ranging, in combination with other solar system data continues to refine some important limits. Satellite laser ranging tracking of geodetic satellites can provide similar tests, but the accuracy is usually limited by gravitational and nongravitational perturbations

    The Attraction of Foreign Manufacturing Investments: Investment Promotion and Agglomeration Economies

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    We study Japanese investments between 1980 and 1992 to assess the effectiveness of state promotion efforts in light of strong agglomeration economies in Japanese investment. Two policy variables are consistently shown to influence the location of investment - foreign trade zones and labor subsidies. We use simulations to explore the impact these policies had on the geographic distribution of Japanese investment. The simulations reveal that in aggregate promotion programs largely offset each other; however, unilateral withdrawal of promotion causes individual states to lose substantial amounts of foreign investment.

    The Management of Defense

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    Precision orbit determination of altimetric satellites

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    The ability to determine accurate global sea level variations is important to both detection and understanding of changes in climate patterns. Sea level variability occurs over a wide spectrum of temporal and spatial scales, and precise global measurements are only recently possible with the advent of spaceborne satellite radar altimetry missions. One of the inherent requirements for accurate determination of absolute sea surface topography is that the altimetric satellite orbits be computed with sub-decimeter accuracy within a well defined terrestrial reference frame. SLR tracking in support of precision orbit determination of altimetric satellites is significant. Recent examples are the use of SLR as the primary tracking systems for TOPEX/Poseidon and for ERS-1 precision orbit determination. The current radial orbit accuracy for TOPEX/Poseidon is estimated to be around 3-4 cm, with geographically correlated orbit errors around 2 cm. The significance of the SLR tracking system is its ability to allow altimetric satellites to obtain absolute sea level measurements and thereby provide a link to other altimetry measurement systems for long-term sea level studies. SLR tracking allows the production of precise orbits which are well centered in an accurate terrestrial reference frame. With proper calibration of the radar altimeter, these precise orbits, along with the altimeter measurements, provide long term absolute sea level measurements. The U.S. Navy's Geosat mission is equipped with only Doppler beacons and lacks laser retroreflectors. However, its orbits, and even the Geosat orbits computed using the available full 40-station Tranet tracking network, yield orbits with significant north-south shifts with respect to the IERS terrestrial reference frame. The resulting Geosat sea surface topography will be tilted accordingly, making interpretation of long-term sea level variability studies difficult

    A new laser-ranged satellite for General Relativity and space geodesy: I. An introduction to the LARES2 space experiment

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    We introduce the LARES 2 space experiment recently approved by the Italian Space Agency (ASI). The LARES 2 satellite is planned for launch in 2019 with the new VEGA C launch vehicle of ASI, ESA and ELV. The orbital analysis of LARES 2 experiment will be carried out by our international science team of experts in General Relativity, theoretical physics, space geodesy and aerospace engineering. The main objectives of the LARES 2 experiment are gravitational and fundamental physics, including accurate measurements of General Relativity, in particular a test of frame-dragging aimed at achieving an accuracy of a few parts in a thousand, i.e., aimed at improving by about an order of magnitude the present state-of-the-art and forthcoming tests of this general relativistic phenomenon. LARES 2 will also achieve determinations in space geodesy. LARES 2 is an improved version of the LAGEOS 3 experiment, proposed in 1984 to measure frame-dragging and analyzed in 1989 by a joint ASI and NASA study

    Fundamental Physics and General Relativity with the LARES and LAGEOS satellites

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    Current observations of the universe have strengthened the interest to further test General Relativity and other theories of fundamental physics. After an introduction to the phenomenon of frame-dragging predicted by Einstein's theory of General Relativity, with fundamental astrophysical applications to rotating black holes, we describe the past measurements of frame-dragging obtained by the LAGEOS satellites and by the dedicated Gravity Probe B space mission. We also discuss a test of String Theories of Chern-Simons type that has been carried out using the results of the LAGEOS satellites. We then describe the LARES space experiment. LARES was successfully launched in February 2012 to improve the accuracy of the tests of frame-dragging, it can also improve the test of String Theories. We present the results of the first few months of observations of LARES, its orbital analyses show that it has the best agreement of any other satellite with the test-particle motion predicted by General Relativity. We finally briefly report the accurate studies and the extensive simulations of the LARES space experiment, confirming an accuracy of a few percent in the forthcoming measurement of frame-dragging.Comment: To be publihed in Nuclear Physics. arXiv admin note: substantial text overlap with arXiv:1306.1826, arXiv:1211.137

    The prognostic value of polymorphonuclear leukocyte elastase in patients with primary breast cancer

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    A variety of serine proteases, including urokinase-type plasminogen activator (uPA), plasmin,and polymorphonuclear leukocyte elastase (PMN-E), have been implicated in the processes of tumor cell invasion and metastasis. Besides degrading of matrix proteins, PMN-E has been shown to be able to cleave and inactivate plasminogen activator inhibitor-1 (PAI-1), the main inhibitor of uPA, and alpha2-antiplasmin, the natural inhibitor of plasmin, thus enabling an uncontrolled matrix degradation by the fibrinolytic enzymes. Because only limited data are available on a relationship between the tumor level of PMN-E and prognosis in primary breast cancer patients, in the present study we have measured with an ELISA the levels of PMN-E (in complex with alpha1-proteinase inhibitor) in cytosolic extracts of 1143 primary breast tumors. Levels of complexed PMN-E have been correlated with the lengths of metastasis-free survival (MFS), relapse-free survival, and overall survival, and a comparison was made with data previously obtained for uPA and PAI-1. Our results show that patients with a high PMN-E level in their primary tumor had a rapid relapse and an early death compared with patients with a low tumor level of PMN-E. This held true for node-negative and node-positive subgroups of patients as well. The relationship of PMN-E with a poor prognosis was especially obvious during short-term follow-up (0-60 months). In Cox multivariate regression analysis, corrected for the traditional prognostic factors, PMN-E was an independent prognostic factor, and high levels of PMN-E were associated with a poor MFS [hazard ratio (HR), 1.63; 95% confidence interval (CI), 1.23-2.16; P < 0.001], relapse-free survival (HR, 1.45; 95% CI, 1.10-1.89; P = 0.01), and overall survival (HR, 1.64; 95% CI, 1.20-2.23; P = 0.003). Furthermore, in all three multivariate models, PMN-E still added significantly to the model after the additional inclusion of the uPA. PMN-E was an independent prognostic factor for MFS even in the multivariate analysis including the traditional clinical prognostic factors and the strong established biochemical prognostic factors uPA and PAI-1. Our present study suggests that PMN-E is associated with breast cancer metastasis, and knowledge of the tumor PMN-E status might be helpful in selecting the appropriate individualized (adjuvant) treatment for patients with breast cancer

    A Test of General Relativity Using the LARES and LAGEOS Satellites and a GRACE Earth's Gravity Model

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    We present a test of General Relativity, the measurement of the Earth's dragging of inertial frames. Our result is obtained using about 3.5 years of laser-ranged observations of the LARES, LAGEOS and LAGEOS 2 laser-ranged satellites together with the Earth's gravity field model GGM05S produced by the space geodesy mission GRACE. We measure μ=(0.994±0.002)±0.05\mu = (0.994 \pm 0.002) \pm 0.05, where μ\mu is the Earth's dragging of inertial frames normalized to its General Relativity value, 0.002 is the 1-sigma formal error and 0.05 is the estimated systematic error mainly due to the uncertainties in the Earth's gravity model GGM05S. Our result is in agreement with the prediction of General Relativity.Comment: 13 pages, 4 figures, published on EPJ

    GRACE Measurements of Mass Variability in the Earth System

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    Monthly gravity field estimates made by the twin Gravity Recovery and Climate Experiment (GRACE) satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers. The annual cycle in the geoid variations, up to 10 millimeters in some regions, peaked predominantly in the spring and fall seasons. Geoid variations observed over South America that can be largely attributed to surface water and groundwater changes show a clear separation between the large Amazon watershed and the smaller watersheds to the north. Such observations will help hydrologists to connect processes at traditional length scales (tens of kilometers or less) to those at regional and global scales
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