Measuring random force noise for LISA aboard the LISA Pathfinder mission

The LTP (LISA Testflight Package), to be flown aboard the ESA / NASA LISA Pathfinder mission, aims to demonstrate drag-free control for LISA test masses with acceleration noise below 30 fm/s^2/Hz^1/2 from 1-30 mHz. This paper describes the LTP measurement of random, position independent forces acting on the test masses. In addition to putting an overall upper limit for all source of random force noise, LTP will measure the conversion of several key disturbances into acceleration noise and thus allow a more detailed characterization of the drag-free performance to be expected for LISA.Comment: 7 pages, 3 figures. To be published in Classical and Quantum Gravity with the proceedings of the 2003 Amaldi Meetin

Characterization of disturbance sources for LISA: torsion pendulum results

A torsion pendulum allows ground-based investigation of the purity of free-fall for the LISA test masses inside their capacitive position sensor. This paper presents recent improvements in our torsion pendulum facility that have both increased the pendulum sensitivity and allowed detailed characterization of several important sources of acceleration noise for the LISA test masses. We discuss here an improved upper limit on random force noise originating in the sensor. Additionally, we present new measurement techniques and preliminary results for characterizing the forces caused by the sensor's residual electrostatic fields, dielectric losses, residual spring-like coupling, and temperature gradients.Comment: 11 pages, 8 figures, accepted for publication Classical and Quantum Gravit

Measuring the LISA test mass magnetic proprieties with a torsion pendulum

Achieving the low frequency LISA sensitivity requires that the test masses acting as the interferometer end mirrors are free-falling with an unprecedented small degree of deviation. Magnetic disturbances, originating in the interaction of the test mass with the environmental magnetic field, can significantly deteriorate the LISA performance and can be parameterized through the test mass remnant dipole moment $\vec{m}_r$ and the magnetic susceptibility $\chi$. While the LISA test flight precursor LTP will investigate these effects during the preliminary phases of the mission, the very stringent requirements on the test mass magnetic cleanliness make ground-based characterization of its magnetic proprieties paramount. We propose a torsion pendulum technique to accurately measure on ground the magnetic proprieties of the LISA/LTP test masses.Comment: 6 pages, 3 figure

Classificação, densidade e parâmetros nutricionais do milho.

Projeto/Plano de Ação: 11.11.11.111

Correlação entre resultados de densidade e classificação de milho realizado por duas empresas.

Projeto/Plano de Ação: 03.10.01.03

Upper limits on stray force noise for LISA

We have developed a torsion pendulum facility for LISA gravitational reference sensor ground testing that allows us to put significant upper limits on residual stray forces exerted by LISA-like position sensors on a representative test mass and to characterize specific sources of disturbances for LISA. We present here the details of the facility, the experimental procedures used to maximize its sensitivity, and the techniques used to characterize the pendulum itself that allowed us to reach a torque sensitivity below 20 fNm /sqrt{Hz} from 0.3 to 10 mHz. We also discuss the implications of the obtained results for LISA.Comment: To be published in Classical and Quantum Gravity, special issue on Amaldi5 2003 conference proceedings (10 pages, 6 figures

Achieving geodetic motion for LISA test masses: ground testing result

The low-frequency resolution of space-based gravitational wave observatories such as LISA (Laser Interferometry Space Antenna) hinges on the orbital purity of a free-falling reference test mass inside a satellite shield. We present here a torsion pendulum study of the forces that will disturb an orbiting test mass inside a LISA capacitive position sensor. The pendulum, with a measured torque noise floor below 10 fNm/sqrt{Hz} from 0.6 to 10 mHz, has allowed placement of an upper limit on sensor force noise contributions, measurement of the sensor electrostatic stiffness at the 5% level, and detection and compensation of stray DC electrostatic biases at the mV level.Comment: 4 pages (revtex4) with 4 figure

On the Possibility of Measuring the Gravitomagnetic Clock Effect in an Earth Space-Based Experiment

In this paper the effect of the post-Newtonian gravitomagnetic force on the mean longitudes $l$ of a pair of counter-rotating Earth artificial satellites following almost identical circular equatorial orbits is investigated. The possibility of measuring it is examined. The observable is the difference of the times required to $l$ in passing from 0 to 2$\pi$ for both senses of motion. Such gravitomagnetic time shift, which is independent of the orbital parameters of the satellites, amounts to 5$\times 10^{-7}$ s for Earth; it is cumulative and should be measured after a sufficiently high number of revolutions. The major limiting factors are the unavoidable imperfect cancellation of the Keplerian periods, which yields a constraint of 10$^{-2}$ cm in knowing the difference between the semimajor axes $a$ of the satellites, and the difference $I$ of the inclinations $i$ of the orbital planes which, for $i\sim 0.01^\circ$, should be less than $0.006^\circ$. A pair of spacecrafts endowed with a sophisticated intersatellite tracking apparatus and drag-free control down to 10$^{-9}$ cm s$^{-2}$ Hz$^{-{1/2}}$ level might allow to meet the stringent requirements posed by such a mission.Comment: LaTex2e, 22 pages, no tables, 1 figure, 38 references. Final version accepted for publication in Classical and Quantum Gravit

Factors Predicting Early Failure of Etanercept in Rheumatoid Arthritis: An Analysis From the Gruppo Italiano di Studio sulla Early Arthritis (Italian Group for the Study of Early Arthritis) Registry

Objectives: This study aims to investigate the factors associated with early discontinuation (within one year) of etanercept (ETA) in rheumatoid arthritis (RA) patients who began ETA as first biologic disease-modifying antirheumatic drug (bDMARD) and who were entered into the Gruppo Italiano di Studio sulla Early Arthritis (Italian Group for the Study of Early Arthritis; GISEA) registry.Patients and methods: This registry-based cohort study included 477 RA patients (95 males, 382 females; median age 53 years; range 18 to 83 years) who began ETA as first bDMARD. Patient demographics, disease features and drugs were re-evaluated after 12 months. Baseline predictors of ETA discontinuation were estimated by univariate and multivariate analyses using Cox regression model.Results: Seventy patients (14.7%) discontinued ETA during the first year (for inefficacy in 55.8%, adverse events in 28.6%, and other reasons in 6.5%). Concurrent conventional synthetic DMARDs (csDMARDs) were reported in 54.3% of patients, mainly methotrexate (MTX), while 52.4% of subjects took low doses of glucocorticoids. Patients stopping ETA more frequently showed one or more comorbidities, mainly cardiovascular diseases (28.6% vs. 15.7% in patients stopping and continuing ETA, respectively, p=0.009). The presence of comorbidities and a combination therapy with csDMARDs other than MTX were independent factors associated with early discontinuation of ETA at multivariate Cox analysis.Conclusion: Although ETA demonstrated a high persistence in biologic-naive RA patients, about 15% of patients discontinued the treatment within 12 months. The presence of comorbidities and a combination therapy with csDMARDs other than MTX were the main factors for an early withdrawal of the drug

Probiotic yogurt with brazilian red propolis: physicochemical and bioactive properties, stability, and shelf life

This study aimed to evaluate the quality parameters in probiotic yogurt produced with Brazilian red propolis to replace potassium sorbate used in conventional yogurt (CY). Microbiological stability and shelf life, physicochemical properties (pH, acidity, chemical composition, and fatty acids), and bioactive properties (phenolic compounds and antioxidant activity) were evaluated. The addition of red propolis (0.05%) to replace the potassium sorbate did not change the pH, acidity, fatty acid profile, chemical composition, or shelf life. Microbiological stability of at least 28 days was achieved, while a drastic reduction in the lactic acid bacteria content was observed in the CY during refrigeration storage. Phenolic total contents were higher than those of the control, and consequently, yogurt with red propolis showed higher antioxidant activity.We thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazilian government, for scholarship support (Finance Code 001), the Dr Cátia Ionara Santos Lucas (INSECTA laboratory, UFRB, Cruz das Almas, Brazil), and the technical team of the Polytechnic Institute of Bragança laboratory (Bragança, Portugal) for their support during the research.info:eu-repo/semantics/publishedVersio