1,030 research outputs found
Will gravitational waves confirm Einstein's General Relativity?
Even if Einstein's General Relativity achieved a great success and overcame
lots of experimental tests, it also showed some shortcomings and flaws which
today advise theorists to ask if it is the definitive theory of gravity. In
this proceeding paper it is shown that, if advanced projects on the detection
of Gravitational Waves (GWs) will improve their sensitivity, allowing to
perform a GWs astronomy, accurate angular and frequency dependent response
functions of interferometers for GWs arising from various Theories of Gravity,
i.e. General Relativity and Extended Theories of Gravity, will be the ultimate
test for General Relativity. This proceeding paper is also a short review of
the Essay which won Honorable Mention at the 2009 Gravity Research Foundation
Awards.Comment: To appear in Proceedings of the 7th International Conference of
Numerical Analysis and Applied Mathematics, Rethymno, Crete (near to Chania),
Greece, 18-22 September 200
A non-geodesic motion in the R^-1 theory of gravity tuned with observations
In the general picture of high order theories of gravity, recently, the R^-1
theory has been analyzed in two different frameworks. In this letter a third
context is added, considering an explicit coupling between the R^-1 function of
the Ricci scalar and the matter Lagrangian. The result is a non-geodesic motion
of test particles which, in principle, could be connected with Dark Matter and
Pioneer anomaly problems.Comment: Accepted for Modern Physics Letters
Gravitomagnetic effect in gravitational waves
After an introduction emphasizing the importance of the gravitomag- netic
effect in general relativity, with a resume of some space-based appli- cations,
we discuss the so-called magnetic components of gravitational waves (GWs),
which have to be taken into account in the context of the total response
functions of interferometers for GWs propagating from ar- bitrary directions.Comment: To appear in Proceedings of the 7th International Conference of
Numerical Analysis and Applied Mathematics, Rethymno, Crete (near to Chania),
Greece, 18-22 September 200
Gravitational Waves Astronomy: a cornerstone for gravitational theories
Realizing a gravitational wave (GW) astronomy in next years is a great
challenge for the scientific community. By giving a significant amount of new
information, GWs will be a cornerstone for a better understanding of
gravitational physics. In this paper we re-discuss that the GW astronomy will
permit to solve a captivating issue of gravitation. In fact, it will be the
definitive test for Einstein's general relativity (GR), or, alternatively, a
strong endorsement for extended theories of gravity (ETG).Comment: To appear in Proceedings of the Workshop "Cosmology, the Quantum
Vacuum and Zeta Functions" for the celebration of Emilio Elizalde's sixtieth
birthday, Barcelona, March 8-10, 201
The production of matter from curvature in a particular linearized high order theory of gravity and the longitudinal response function of interferometers
The strict analogy between scalar-tensor theories of gravity and high order
gravity is well known in literature. In this paper it is shown that, from a
particular high order gravity theory known in literature, it is possible to
produce, in the linearized approch, particles which can be seen like massive
scalar modes of gravitational waves and the response of interferometers to this
type of particles is analyzed. The presence of the mass generates a
longitudinal force in addition of the transverse one which is proper of the
massless gravitational waves and the response of an arm of an interferometer to
this longitudinal effect in the frame of a local observer is computed. This
longitudinal response function is directly connected with the function of the
Ricci scalar in the particular action of this high order theory. Important
conseguences from a theoretical point of view could arise from this approach,
because it opens to the possibility of using the signals seen from
interferometers to understand which is the correct theory of gravitation.Comment: Accepted for Journal of Cosmology and Astroparticle Physic
In situ characterisation of readhesion treatments for ceiling paintings using unilateral NMR
Ceiling and wall paintings pose significant challenges for historic house management due to their position at the interface between the environment and the building. Tight restrictions to modifications on built heritage prevent total control of the environment, resulting in temperature and humidity fluctuations. Different hygrothermal responses within the wall painting stratigraphy frequently lead to fracturing and lifting of paint layers, necessitating remedial conservation to readhere areas of detachment. Assessing the success of readhesion interventions is difficult due to the hidden nature of the treatment and, often, limited access. This paper presents comparative results of two different adhesive treatments employed during the conservation of the baroque ceiling painting in the Queen's Staircase at Hampton Court Palace, analysed with unilateral nuclear magnetic resonance (NMR). This non-invasive technique enabled monitoring of the adhesive systems, based on Jun Funori and BEVA® 371 adhesives, up to a depth of 3,500 μm into the ceiling by providing specially resolved proton density profiles before and after treatment. The results offer a unique and pertinent assessment of treatment areas within a strictly limited timeframe. It is shown that the solvent carrier leaves the system within 24 hours and that the ultimate deposition of the adhesive can be identified
Characterization of power transistors as high dose dosimeters
A bipolar transistor, previously investigated as a possible radiation dosimeter and tested under industrial irradiation conditions in high-activity gamma and high-energy, high-power electron beam facilities has been subjected to stability test in order to understand its behaviour and help to improve its performances. Charge carrier lifetime was measured for several sets of transistors which were then irradiated with various doses (3-60 kGy): seven sets with Co-60 gamma rays and eight with a 10MeV electron beam. After irradiation all the transistors were measured and each set was divided into three groups: one group was left untreated, the second group was heated at 100 degrees C for 30 minutes and the third group was heated at 150 degrees C for 30 minutes, for testing the stability of the lifetime. Our data showed that heat treatment quite successfully eliminates post-irradiation changes in the response. Response measurements of the irradiated transistors, heat-treated and untreated, were carried out at room temperature over several weeks after irradiation to establish post-irradiation stability and assess if these transistors could be used for recording dose history. Calibration curves in the range 3-60 kGy for the thermally treated and untreated devices are presented. Dependence of the response of the transistors on the temperature of the measurements in the range 20-50 degrees C is reported
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