U Geminorum: a test case for orbital parameters determination

High-resolution spectroscopy of U Gem was obtained during quiescence. We did not find a hot spot or gas stream around the outer boundaries of the accretion disk. Instead, we detected a strong narrow emission near the location of the secondary star. We measured the radial velocity curve from the wings of the double-peaked H$\alpha$ emission line, and obtained a semi-amplitude value that is in excellent agreement with the obtained from observations in the ultraviolet spectral region by Sion et al. (1998). We present also a new method to obtain K_2, which enhances the detection of absorption or emission features arising in the late-type companion. Our results are compared with published values derived from the near-infrared NaI line doublet. From a comparison of the TiO band with those of late type M stars, we find that a best fit is obtained for a M6V star, contributing 5 percent of the total light at that spectral region. Assuming that the radial velocity semi-amplitudes reflect accurately the motion of the binary components, then from our results: K_em = 107+/-2 km/s; K_abs = 310+/-5 km/s, and using the inclination angle given by Zhang & Robinson(1987); i = 69.7+/-0.7, the system parameters become: M_WD = 1.20+/-0.05 M_sun,; M_RD = 0.42+/-0.04 M_sun; and a = 1.55+/- 0.02 R_sun. Based on the separation of the double emission peaks, we calculate an outer disk radius of R_out/a ~0.61, close to the distance of the inner Lagrangian point L_1/a~0.63. Therefore we suggest that, at the time of observations, the accretion disk was filling the Roche-Lobe of the primary, and that the matter leaving the L_1 point was colliding with the disc directly, producing the hot spot at this location.Comment: 36 pages, 14 figures, ccepted for publication in A

Identification of structural parameters from helicopter dynamic test data

A method is presented for obtaining the mass, stiffness, and damping parameters of a linear mathematical model, having fewer degrees of freedom than the structure it represents, directly from dynamic response measurements on the actual helicopter without a priori knowledge of the physical characteristics of the fuselage. The only input information required in the formulation is the approximate natural frequency of each mode and mobility data measured proximate to these frequencies with sinusoidal force excitation applied at only one point on the vehicle. The practicality and numerical soundness of the theoretical development was demonstrated through a computer simulation of an experimental program

Testing for Time Dependence in Parameters

This paper proposes a new test based on a Fourier series expansion to approximate the unknown functional form of a nonlinear time-series model. The test specifically allows for structural breaks, seasonal parameters and time-varying parameters. The test is shown to have evry good size and power properties. However, it is not especially good in detecting nonlinearity in variables. As such, the test can help determine whether an observed rejection of the joint null hypothesis of linearity and time invariant parameters is due to time-varying coefficients of a nonliearity in variables.time varying parameters; fourier-series; nuisance parameters

On APF Test for Poisson Process with Shift and Scale Parameters

We propose the goodness of fit test for inhomogeneous Poisson processes with unknown scale and shift parameters. A test statistic of Cramer-von Mises type is proposed and its asymptotic behavior is studied. We show that under null hypothesis the limit distribution of this statistic does not depend on unknown parameters.Comment: 15 page

The Incidental Parameters Problem in Testing for Remaining Cross-section Correlation

In this paper we consider the properties of the Pesaran (2004, 2015a) CD test for cross-section correlation when applied to residuals obtained from panel data models with many estimated parameters. We show that the presence of period-specific parameters leads the CD test statistic to diverge as length of the time dimension of the sample grows. This result holds even if cross-section dependence is correctly accounted for and hence constitutes an example of the Incidental Parameters Problem. The relevance of this problem is investigated both for the classical Time Fixed Effects estimator as well as the Common Correlated Effects estimator of Pesaran (2006). We suggest a weighted CD test statistic which re-establishes standard normal inference under the null hypothesis. Given the widespread use of the CD test statistic to test for remaining cross-section correlation, our results have far reaching implications for empirical researchers.Comment: 84 pages, 11 table

Subchronic Toxicity of Green Algae (Spyrogyra SP.) Ethanolic Extract on Hematologic Parameters

Green Algae, an organism with active substance such as phytomelatonin, has potential to be developed as Indonesian traditional medicine. As the long term addition of Green Algae ethanol extract (Ekstrak etanol ganggang hijau, EEGH) influences the hematology system, in this paper, the safety test was done to ensure the safety of its use through subchronic toxicity test of EEGH on the hematology parameters of Wistar rats. The test group consisted of three groups treated with EEGH 100 mg/kg, 200 mg/kg, and 400 mg/kg, while the control group was given by 0.5% CMC-Na, with 8 rats each respectively. By using blood samples taken from orbital sinus on the 29th day, common hematologic parameters (erythrocytes, leukocytes, and hemoglobin level), the parameters of hemostasis (platelets, pT, aPTT, BT) and immune parameters (Differential Leukocytes Counts include neutrophils segment, lymphocytes, monocytes, and eosinophils) were finally observed and showed that the 28 days-addition of EEGH increase the hematological parameters of Wistar rats