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[en] After reviewing the reasons of the existence of a new long range force in Nature, the limits that may be placed upon this new long-range force which couples to mass are presented. Some positive evidence that it exists are presented (measurements of 6N, gravity gradient anomaly)
[en] The results of geophysical and laboratory measurements of Newton's constant of gravitation, seem to disagree by one percent. Attempts to explain this have led to the revival of the proposal for a fifth interaction in Nature. The experimental results on measurements of G and tests of Newton's inverse square law are reviewed. The recent reanalysis of the Eoetvoes experiment and proposals for new experiments are discussed. (Author)
[pt]Os resultados de medicoes geofisicas e de laboratorio da constante gravitacional de Newton, parecem discordar em cerca de um por cento. Tentativas de explicar isto tem levado a um renascimento da proposta de uma quinta interacao na Natureza. Os resultados experimentais de medicoes de G e testes da lei do inverso do quadrado de Newton, sao revistos. A recente analise da experiencia de Eoetvoes e propostas de novas experiencias, sao discutidas. (S.D.)
[en] An instrument was developed for the direct mass flow calibration of gas flowmeters that does not require measurement of temperature, pressure, or specific volume. This instrument measures the weight of gas collected in a container and makes measuring those thermodynamic variables unnecessary. The need to measure the weight of the gas container is eliminated by submerging it in a liquid (presently water) and balancing its weight with the force of buoyancy. The accuracy of this Gravimetric Calibrator is unaffected by the pressure and temperature of the gas. The Calibrator can also measure reactive, corrosive, and non-ideal gases. The container remains connected to the process by a torsion capillary, and a load cell measures the changing gas weight continuously throughout the measuring process. A prototype was designed for gas flows ranging from 1 sccm of hydrogen to 10,000 sccm of tungsten hexafluoride, constructed, tested, and used to calibrate flow devices. Experience with the prototype and results are presented, and plans for further developments are discussed
[en] Limits on the long-term stability and accuracy of a second generation cold atom gravimeter are investigated. We demonstrate a measurement protocol based on four interleaved measurement configurations, which allows rejection of most of the systematic effects, but not those related to Coriolis acceleration and wave-front distortions. Both are related to the transverse motion of the atomic cloud. Carrying out measurements with opposite orientations with respect to the Earth's rotation vector direction allows us to separate the effects and correct for the Coriolis shift. Finally, measurements at different atomic temperatures are presented and analyzed. In particular, we show the difficulty of extrapolating these measurements to zero temperature, which is required in order to correct for the bias due to wave-front distortions.
[en] The problem of precise measurement of the gravitational constant is considered. It is shown that several absolutely identical installations operating for a long time is automatic mode, which measure the important fundamental constant simultaneously in different points, should be developed to solve successfully the problems of metrological security of the gravitational constant measurement
[en] Complete text of publication follows. It is well known that the exposure to particulate matter (PM) during school-age, when children are in their growing stage, can have lifelong adverse effects on their health. Because of these facts it is important to analyse PM in such places where children stay in a limited space during long-term periods. An average schoolchild spends at least six to eight hours a day in an indoor environment. Thus the more detailed knowledge of the air parameters of scholastic environments is particularly important. In this study our aim was to measure those parameters which might help the better estimation of the PM impact on the health of the children/students and teachers in autumn winter season in different educational institutions in the centre of Debrecen, Hungary. Two schools (a primary and a secondary grammar) and a kindergarten were selected for the study. Coarse and fine mass concentrations, elemental composition and mass size distributions were determined in selected microenvironments. These were different classrooms, school yards, gymnasiums, a computer lab, a chemical lab and a so-called salt-room. The elemental composition (for Z ≥ 13) was determined by PIXE and the mass concentrations of particulate matter were determined by gravimetry. In the case of the kindergarten two cascade impactors were also deployed to provide size distribution. In all cases the coarse concentrations of PM were higher inside the educational buildings than in the outer air, and every case the PM10 concentration exceeded the EU air quality standard (Fig. 1). The highest values were measured in the gymnasiums which could be explained by the activities. We observed increased PM concentrations in the lower educational levels. The fine concentration inside the buildings did not differ significantly from the air outside. We did not detect big differences between the indoor and outdoor elemental compositions, but found differences in the elemental concentrations. Based on the mass size distribution values significant differences were found between the salt and the gymnastic room. In the salt room, where children were allowed only to sit, lower concentration values and smaller particle sizes were detected than in the other room where children did exercises and gymnastics. In the light of these results further aerosol characterization studies is needed to provide more accurate information about the sources and the possible health effects of ambient aerosol in educational environments. Acknowledgements. This work was supported by the Hungarian Research Fund OTKA and the EGT Norwegian Financial Mechanism Programme (contract no. NNF78829) and the Janos Bolyai Research Scholarship of the HAS.
[en] Was Newton right in thinking that the pull of gravity on a body is governed by its inertial mass? If he was, then all bodies have the same free fall acceleration, as Galileo tried to check in his classic but not very accurate experiments at the leaning tower of Pisa. This equivalence of inertial and gravitational mass went on to become a basic principle in Einstein's general theory of relativity, and so is a cornerstone in our understanding of the Universe