Structure du terrier, reproduction et comportement des jeunes chez le poisson amphibie Periophtalmus sobrinus eggert

Les observations faites à Madagascar sur le comportement reproducteur de P. sobrinus ont permis de préciser un certain nombre de points. 1°) Le terrier comprend deux courtes galeries d’accès dont l’orifice est surmonté d’un rempart. Elles confluent en une troisième galerie qui s’enfonce verticalement dans la vase et peut atteindre une profondeur de 80 cm (moyenne : 36 cm). Du tiers inférieur de cette galerie profonde part un diverticule latéral, long d’une dizaine de centimètres, orienté obliquement vers le haut. 2°) A l’issue de la parade nuptiale, la ponte est déposée sur les parois du diverticule. 3°) Le mâle assure la garde des œufs. 4°) Le développement complet des œufs exige des périodes d’émersion de la ponte. A la limite, si l’atmosphère est saturée d’humidité, une seule immersion est indispensa ble, celle qui permet la libération très rapide (2 à 10 secondes) des alevins. 5°) Dès l’éclosion, les larves font preuve d’un phototropisme positif. Elles ne sont pas grégaires. 6°) L’apparition dans les mangroves de Tuléar des jeunes Périophtalmes fraîchement métamorphosés s’étage de fin octobre à fin juin. On les rencontre souvent par groupes denses, très localisés. 7°) Dès la métamorphose, le comportement des -Periephtal- mes immatures diffère de celui des adultes par la moin dre ritualisation de leurs conduites apressives, ainsi que par l’absence des activités de creusement.A study of the reproductive behaviour of Periophtalmus sobrinus Eggert has been carried out in the mangrove swamps of Tulear, Madagascar. The mudskipper’s burrow has two short entrance galeries whose openings are surrounded by a circular wall. These galeries meet to form a tunnel which enters the mud as deep as 80 cm. From the lower third of this tunnel starts a side branch, about ten centimeters long, going upwards. After the sexual display, the female lays its eggs on the walls of the side branch. Then the male remains alone in the burrow, caring for the eggs. To achieve complete development the eggs need periods during which they remain out of water. In a very moist atmos phere, no more than one period of immension is indispensable, during which the fry hatchs very rapidly (2 to 10 sec.). As soon as they are free, larvae show a positive phototropism. No gregarious behaviour has then been observed. In the mangrove swamps of Tulear, young mudskippers recently metamorphosed can be found from the end of October to the end of June. They are often found in dense groups, very localized. There are few differences between the behaviour of adult Mudskippers and that of young ones as soon as they are metamor phosed. Yet no burrowing has been observed among the small fish and their aggressive encounters are less ritualized than the agonistic activities of sexually mature individuals

A high accuracy method for the simulation of non-ideal optical cavities

We present an algorithm able to represent with a high accuracy any kind of stable cavity, even when many static or dynamical defects are present, like misalignments, curvature errors, surface irregularities, substrate inhomogeneities... We first present the theory, giving ideas on its validity domain, and a discussion of its accuracy in terms of a RMS phase error, which is found to be negligible compared to the phase noise due to roughness of optical surfaces. Then we show that the well-known features of ideal resonant cavities are found by the algorithm with a good accuracy. This tool can help for designing laser cavities, mode cleaners, or passive Fabry-Perot standards ; as an example, some results are presented concerning the design of a very long cavity planned for interferometric purposes

Network sensitivity to geographical configuration

Gravitational wave astronomy will require the coordinated analysis of data from the global network of gravitational wave observatories. Questions of how to optimally configure the global network arise in this context. We have elsewhere proposed a formalism which is employed here to compare different configurations of the network, using both the coincident network analysis method and the coherent network analysis method. We have constructed a network model to compute a figure-of-merit based on the detection rate for a population of standard-candle binary inspirals. We find that this measure of network quality is very sensitive to the geographic location of component detectors under a coincident network analysis, but comparatively insensitive under a coherent network analysis.Comment: 7 pages, 4 figures, accepted for proceedings of the 4th Edoardo Amaldi conference, incorporated referees' suggestions and corrected diagra

A note on light velocity anisotropy

It is proved that in experiments on or near the Earth, no anisotropy in the one-way velocity of light may be detected. The very accurate experiments which have been performed to detect such an effect are to be considered significant tests of both special relativity and the equivalence principleComment: 8 pages, LaTex, Gen. Relat. Grav. accepte

Is it possible to detect gravitational waves with atom interferometers?

We investigate the possibility to use atom interferometers to detect gravitational waves. We discuss the interaction of gravitational waves with an atom interferometer and analyze possible schemes

Coherent Bayesian inference on compact binary inspirals using a network of interferometric gravitational wave detectors

Presented in this paper is a Markov chain Monte Carlo (MCMC) routine for conducting coherent parameter estimation for interferometric gravitational wave observations of an inspiral of binary compact objects using data from multiple detectors. The MCMC technique uses data from several interferometers and infers all nine of the parameters (ignoring spin) associated with the binary system, including the distance to the source, the masses, and the location on the sky. The Metropolis-algorithm utilises advanced MCMC techniques, such as importance resampling and parallel tempering. The data is compared with time-domain inspiral templates that are 2.5 post-Newtonian (PN) in phase and 2.0 PN in amplitude. Our routine could be implemented as part of an inspiral detection pipeline for a world wide network of detectors. Examples are given for simulated signals and data as seen by the LIGO and Virgo detectors operating at their design sensitivity.Comment: 10 pages, 4 figure

A Mission to Explore the Pioneer Anomaly

The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. These spacecraft had exceptional acceleration sensitivity. However, analysis of their radio-metric tracking data has consistently indicated that at heliocentric distances of $\sim 20-70$ astronomical units, the orbit determinations indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of $\sim(5.99 \pm 0.01)\times 10^{-9}$ Hz/s, which can be interpreted as a constant sunward acceleration of each particular spacecraft of $a_P = (8.74 \pm 1.33)\times 10^{-10} {\rm m/s^2}$. This signal has become known as the Pioneer anomaly. The inability to explain the anomalous behavior of the Pioneers with conventional physics has contributed to growing discussion about its origin. There is now an increasing number of proposals that attempt to explain the anomaly outside conventional physics. This progress emphasizes the need for a new experiment to explore the detected signal. Furthermore, the recent extensive efforts led to the conclusion that only a dedicated experiment could ultimately determine the nature of the found signal. We discuss the Pioneer anomaly and present the next steps towards an understanding of its origin. We specifically focus on the development of a mission to explore the Pioneer Anomaly in a dedicated experiment conducted in deep space.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020", 19-21 April 2005, ESTEC, Noordwijk, The Netherland

Fundamental Physics with the Laser Astrometric Test Of Relativity

The Laser Astrometric Test Of Relativity (LATOR) is a joint European-U.S. Michelson-Morley-type experiment designed to test the pure tensor metric nature of gravitation - a fundamental postulate of Einstein's theory of general relativity. By using a combination of independent time-series of highly accurate gravitational deflection of light in the immediate proximity to the Sun, along with measurements of the Shapiro time delay on interplanetary scales (to a precision respectively better than 0.1 picoradians and 1 cm), LATOR will significantly improve our knowledge of relativistic gravity. The primary mission objective is to i) measure the key post-Newtonian Eddington parameter \gamma with accuracy of a part in 10^9. (1-\gamma) is a direct measure for presence of a new interaction in gravitational theory, and, in its search, LATOR goes a factor 30,000 beyond the present best result, Cassini's 2003 test. The mission will also provide: ii) first measurement of gravity's non-linear effects on light to ~0.01% accuracy; including both the Eddington \beta parameter and also the spatial metric's 2nd order potential contribution (never measured before); iii) direct measurement of the solar quadrupole moment J2 (currently unavailable) to accuracy of a part in 200 of its expected size; iv) direct measurement of the "frame-dragging" effect on light by the Sun's gravitomagnetic field, to 1% accuracy. LATOR's primary measurement pushes to unprecedented accuracy the search for cosmologically relevant scalar-tensor theories of gravity by looking for a remnant scalar field in today's solar system. We discuss the mission design of this proposed experiment.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020," 19-21 April 2005, ESTEC, Noodrwijk, The Netherland

Reference frames and rigid motions in relativity: Applications

The concept of rigid reference frame and of constricted spatial metric, given in the previous work [\emph{Class. Quantum Grav.} {\bf 21}, 3067,(2004)] are here applied to some specific space-times: In particular, the rigid rotating disc with constant angular velocity in Minkowski space-time is analyzed, a new approach to the Ehrenfest paradox is given as well as a new explanation of the Sagnac effect. Finally the anisotropy of the speed of light and its measurable consequences in a reference frame co-moving with the Earth are discussed.Comment: 13 pages, 1 figur

Test of Special Relativity and Equivalence principle from K Physics

A violation of Local Lorentz Invariance (VLI) and hence the special theory of relativity or a violation of equivalence principle (VEP) in the Kaon system can, in principle, induce oscillations between $K^0$ and $\bar{K}^0$. We construct a general formulation in which simultaneous pairwise diagonalization of mass, momemtum, weak or gravitational eigenstates is not assumed. %and the maximum attainable %velocities of the velocity eigenstates are different. We discuss this problem in a general way and point out that, as expected, the VEP and VLI contributions are indistinguishable. We then insist on the fact that VEP or VLI can occur even when CPT is conserved. A possible CP violation of the superweak type induced by VEP or VLI is introduced and discussed. We show that the general VEP mechanism (or the VLI mechanism, but not both simultaneously), with or without conserved CPT, could be clearly tested experimentally through the energy dependence of the $K_L-K_S$ mass difference and of $\eta_{+-}$, $\eta_{00}$, $\delta$. Constraints imposed by present experiments are calculated.Comment: Latex, 15 pages, 1 figure, version to appear in Phys. Rev.