[en] More than seventy years ago. Einstein himself predicted that the gravitational field produced by a variable source must propagate as radiation. But it has been impossible, up to known, to detect this phenomenon. In this paper and in a forecoming second part, the situation is reviewed as well as the theoretical and practical aspects of the construction of future gravitational antennae. (Author)

[en] The present work is developed in the searching for monochromatic gravitational waves signals in ALLEGRO's data. We have two procedures for data analysis based on the periodogram of Welch, which a method for the detection of monochromatic signals in the middle of noise which basically makes power spectrum estimates using averaged modified periodograms. By using this method it was possible to obtain a power spectrum for the data which reinforce peaks due to monochromatic signals. The two procedures of analysis for the years 1997 and 1999, were focused on monitoring a peak that appears in the spectral density of ALLEGRO's detector, so called 'mystery mode' (near 887 Hz). We look for variations in the frequency of the mystery mode that agree with the variation of the Doppler effect. In the rst analysis we have used by the variation of daily and annual Doppler shift. For the second one, we have only searched annual Doppler shift. We have applied the periodogram of Welch in both tests in the raw data of the detector in the search for a real signal and we found some peaks that can be candidates of gravitational radiation only the second analysis. In order to test the method we used in both analysis a simulated gravitational wave signal modulated by the Doppler effect injected in the data. We detected in both methods the artificial signal of GW simulated. Therefore we have reason to conclude that both methods are efficient in the search for monochromatic signals. (author)

[en] The law of gravitation has been tested at distances of less than 1 cm using a dynamic field method. For an additional Yukawa term with a range of λ = 7.1 mm, a relative coupling constant to the Newtonian potential, α = (0.1 +- 1.1) x 10/sup -2/, was obtained

No abstract available

[en] In this work we constructed a two modes matched digital filter for a burst signal of gravitational radiation. The source is a binary black hole system, where this one is in coalescence time and has 0.5 solar mass. For determination of waveform, we have utilized the equations of the General Relativity Theory, and the Friedmann's theory for the expansion of the universe. We considered the formation of black holes in the very early universe when the temperature was about 1 GeV. The characteristics of the ALLEGRO detector were studied and we showed that this detector is sensitive to the studied signal. The events rate calculated are 5 x 10^-2 events per year and various per year for the local group. The power spectral density curve of the noises was determined. With the data of the signal and the noise we obtained the coefficients of the digital filter and elaborated the computer routines for the signals analysis. After filtering the data of the year 1997, we identified several candidates for gravitational wave. We showed that the constructed filter is more effective than the previous one because the temperature of the noise was reduced. We also demonstrated that the filters for impulsive sources have the characteristic of the detect signals of another types of impulsive sources. (author)

[en] This Letter is a generalization of previous results on gravitational waves (GWs) from f(R) theories of gravity. In some previous papers, particular f(R) theories have been linearized for the first time in the literature. Now, the process is further generalized, showing that every f(R) theory can be linearized producting a third massive mode of gravitational radiation. In this framework, previous results are particular cases of the more general problem that is discussed in this Letter. The potential detectability of such massive GWs with LISA is also discussed with the auxilium of longitudinal response functions

[en] Based on the new metric theory of gravitation suggested by the author of this article, it gives a possible theoretical interpretation on the famous experiment done by D.R. Long in 1976, i.e. the distance-dependent effect of the gravitational constant in Newton's theory of gravitation.

[en] A theory of gravitation is proposed which exhibits the property of saturation of the gravitational forces at small distances

[en] The Eotvos method to investigate the dependence of the Earth attraction on the substance considered is discussed in terms of the recently proposed interaction of intermediate range. A null result of the Eotvos experiment is to be expected in a flat, horizontal and symmetric environment. Significant results, can, however, be expected in the presence of a steep slope of the soil or of other sizeable asymmetries. The comparison of the Eotvos results with other geophysical information is rediscussed accordingly

No abstract available