57 research outputs found
Will the recently approved LARES mission be able to measure the Lense-Thirring effect at 1%?
After the approval by the Italian Space Agency of the LARES satellite, which
should be launched at the end of 2009 with a VEGA rocket and whose claimed goal
is a about 1% measurement of the general relativistic gravitomagnetic
Lense-Thirring effect in the gravitational field of the spinning Earth, it is
of the utmost importance to reliably assess the total realistic accuracy that
can be reached by such a mission. The observable is a linear combination of the
nodes of the existing LAGEOS and LAGEOS II satellites and of LARES able to
cancel out the impact of the first two even zonal harmonic coefficients of the
multipolar expansion of the classical part of the terrestrial gravitational
potential representing a major source of systematic error. While LAGEOS and
LAGEOS II fly at altitudes of about 6000 km, LARES will be placed at an
altitude of 1450 km. Thus, it will be sensitive to much more even zonals than
LAGEOS and LAGEOS II. Their corrupting impact \delta\mu has been evaluated by
using the standard Kaula's approach up to degree L=70 along with the sigmas of
the covariance matrices of eight different global gravity solutions
(EIGEN-GRACE02S, EIGEN-CG03C, GGM02S, GGM03S, JEM01-RL03B, ITG-Grace02s,
ITG-Grace03, EGM2008) obtained by five institutions (GFZ, CSR, JPL, IGG, NGA)
with different techniques from long data sets of the dedicated GRACE mission.
It turns out \delta\mu about 100-1000% of the Lense-Thirring effect. An
improvement of 2-3 orders of magnitude in the determination of the high degree
even zonals would be required to constrain the bias to about 1-10%.Comment: Latex, 15 pages, 1 table, no figures. Final version matching the
published one in General Relativity and Gravitation (GRG
The role of cytokine gene polymorphisms in the pathogenesis of abdominal aortic aneurysms: A case-control study
AbstractBackground: Cytokines are the primary mediators of inflammation and also influence matrix metalloproteinase expression, both of which are important in development of abdominal aortic aneurysm (AAA). A significant, but as yet unknown, familial factor contributes to the pathogenesis of AAA. Many cytokine genes contain polymorphic sites, some of which affect cytokine production in vitro. Cytokine gene polymorphisms may therefore influence the pathogenesis of AAA. The purpose of this study was to determine whether there is any association between cytokine gene polymorphisms and AAA. Methods and Results: This case-control study comprised 100 patients with AAA and 100 age-matched and sex-matched control subjects. For each case and control subject in the study, genotypes at the following cytokine gene polymorphic loci were determined: interleukin (IL)-1ÎČ +3953, IL-6 â174, IL-10 â1082, IL-10 â592, and tumor necrosis factors-α â308. Allele and genotype frequencies were compared between AAA and control groups, and odds ratios (OR) were calculated for the presence of AAA with each allele at each locus examined as risk factors. The IL-10 â1082 A allele was significantly more common in the AAA group than the control group (P =.03). The OR for the IL-10 â1082 A allele as a risk factor for AAA was 1.8 (95% confidence interval, 0.9-3.6). Discussion: These associations suggest a significant role for IL-10 in the pathogenesis of AAA. This association of AAA with the IL-10 â1082 A allele is also biologically plausible; the IL-10 â1082 A allele is associated with low IL-10 secretion, and it may be that AAA develops in patients who are unable to mount the same anti-inflammatory response as those who do not have AAA. (J Vasc Surg 2003;37:999-1005.
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
SN 2012ec: mass of the progenitor from PESSTO follow-up of the photospheric phase
We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L = 0.9 Ă 1042âergâsâ1 and duration âŒ90 d, which is somewhat shorter than standard Type II-P supernovae (SNe). We estimate the nickel mass M(56Ni) = 0.040 ± 0.015âMâ from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6âMâ, an initial progenitor radius of 1.6 Ă 1013âcm and an explosion energy of 1.2âfoe. These estimates agree with an independent study of the progenitor star identified in pre-explosion images, for which an initial mass of M = 14-22âMâ was determined. We have applied the same analysis to two other Type II-P SNe (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with the standardized candle method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators
The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles
In the G0 experiment, performed at Jefferson Lab, the parity-violating
elastic scattering of electrons from protons and quasi-elastic scattering from
deuterons is measured in order to determine the neutral weak currents of the
nucleon. Asymmetries as small as 1 part per million in the scattering of a
polarized electron beam are determined using a dedicated apparatus. It consists
of specialized beam-monitoring and control systems, a cryogenic hydrogen (or
deuterium) target, and a superconducting, toroidal magnetic spectrometer
equipped with plastic scintillation and aerogel Cerenkov detectors, as well as
fast readout electronics for the measurement of individual events. The overall
design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method
An Assessment of the Systematic Uncertainty in Present and Future Tests of the Lense-Thirring Effect with Satellite Laser Ranging
We deal with the attempts to measure the Lense-Thirring effect with the
Satellite Laser Ranging (SLR) technique applied to the existing LAGEOS and
LAGEOS II terrestrial satellites and to the recently approved LARES
spacecraft.The first issue addressed here is: are the so far published
evaluations of the systematic uncertainty induced by the bad knowledge of the
even zonal harmonic coefficients J_L of the multipolar expansion of the Earth's
geopotential reliable and realistic?
Our answer is negative. Indeed, if the differences Delta J_L among the even
zonals estimated in different Earth's gravity field global solutions from the
dedicated GRACE mission are assumed for the uncertainties delta J_L instead of
using their covariance sigmas sigma_JL, it turns out that the systematic
uncertainty \delta\mu in the Lense-Thirring test with the nodes Omega of LAGEOS
and LAGEOS II may be up to 3 to 4 times larger than in the evaluations so far
published () based on the use of the sigmas of one model at a time
separately. The second issue consists of the possibility of using a different
approach in extracting the relativistic signature of interest from the
LAGEOS-type data. The third issue is the possibility of reaching a realistic
total accuracy of 1% with LAGEOS, LAGEOS II and LARES, which should be launched
in November 2009 with a VEGA rocket. While LAGEOS and LAGEOS II fly at
altitudes of about 6000 km, LARES will be likely placed at an altitude of 1450
km. Thus, it will be sensitive to much more even zonals than LAGEOS and LAGEOS
II. Their corrupting impact has been evaluated with the standard Kaula's
approach up to degree L=60 by using Delta J_L and sigma_JL; it turns out that
it may be as large as some tens percent.Comment: LaTex, 19 pages, 1 figure, 12 tables. Invited and refereed
contribution to The ISSI Workshop, 6-10 October 2008, on The Nature of
Gravity Confronting Theory and Experiment in Space To appear in Space Science
Review
Synchronous dual primary ovarian and endometrial carcinomas
OBJECTIVES: The synchronous occurrence of carcinoma confined to the ovary and endometrium presents a diagnostic and therapeutic dilemma. These tumors have been variously staged as FIGO Stage IIA ovarian carcinoma, Stage III endometrial carcinoma, or synchronous dual primary carcinomas. Accumulating evidence suggests such patients have a favorable outcome. This retrospective study was undertaken to review our experience with these fascinating tumors. METHODS: The clinical records and the pathologic findings of 16 patients with synchronous dual primary ovarian and endometrial carcinomas were reviewed. RESULTS: The median age was 51 years. Abnormal uterine bleeding was the most common presenting symptom (70%). All patients had Stage I ovarian and endometrial carcinomas. Fourteen patients (88%) had endometrioid carcinoma in both sites, while two patients (12%) had dissimilar histology. For 15 patients (94%), the grade of both tumors was identical. Only three (19%) patients had myometrial invasion, with less than 50% involvement in each case. All patients underwent surgical staging, 11 (70%) of whom received adjuvant radiation or chemotherapy. The five patients treated with surgery alone had Grade 1 endometrioid tumors. The only relapse occurred in a patient with a clear cell component in both sites. No patient has died of disease. CONCLUSIONS: Patients with synchronous dual primary carcinomas appear to have a more favorable prognosis than that expected with Stage IIA ovarian or Stage III endometrial carcinoma (100% vs. 63% or 42% survival at 3 years, respectively). The excellent survival for patients with Grade 1 dual endometrioid tumors treated with surgery alone suggests that adjuvant therapy may not be necessary for this sub-group.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30414/1/0000034.pd
SN 2012ec: Mass of the progenitor from PESSTO follow-up of the photospheric phase
We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L = 0.9 Ă 1042 erg sâ1 and duration âŒ90 d, which is somewhat shorter than standard Type II-P supernovae (SNe). We estimate the nickel mass M(56Ni) = 0.040 ± 0.015 M from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6 M, an initial progenitor radius of 1.6 Ă 1013 cm and an explosion energy of 1.2 foe. These estimates agree with an independent study of the progenitor star identified in
pre-explosion images, for which an initial mass of M = 14â22 M was determined. We have applied the same analysis to two other Type II-P SNe (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with
the standardized candle method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators
Global data on earthworm abundance, biomass, diversity and corresponding environmental properties
14 p.Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change
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