Modal Series Expansions for Plane Gravitational Waves

[EN] Propagation of gravitational disturbances at the speed of light is one of the key predictions of the General Theory of Relativity. This result is now backed indirectly by the observations of the behavior of the ephemeris of binary pulsar systems. These new results have increased the interest in the mathematical theory of gravitational waves in the last decades, and severalmathematical approaches have been developed for a better understanding of the solutions. In this paper we develop a modal series expansion technique in which solutions can be built for plane waves from a seed integrable function. The convergence of these series is proven by the Raabe-Duhamel criteria, and we show that these solutions are characterized by a well-defined and finite curvature tensor and also a finite energy content.Acedo Rodríguez, L. (2016). Modal Series Expansions for Plane Gravitational Waves. Gravitation and Cosmology. 22(3):251-257. doi:10.1134/S0202289316030026S251257223A. Einstein and N. Rosen, Journal of the Franklin Institute 223, 43–54 (1937).N. Rosen, Gen. Rel. Grav. 10, 351–364 (1979).C. Sivaram, Bull. Astr. Soc. India 23, 77–83 (1995).J. M. Weisberg, D. J. Nice, and J. H. Taylor, Astroph. J. 722, 1030–1034(2010); arXiv: 1011.0718.B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), Phys. Rev. Lett. 116, 061102 (2016).J. B. Griffiths, Colliding waves in general relativity (Clarendon, Oxford, 1991).S. Chandrasekhar, The mathematical theory of black holes (Clarendon, Oxford, 1983).D. Bini, V. Ferrari and J. Ibañez, Nuovo Cim. B 103, 29–44 (1989).L. Acedo, G. González-Parra, and A. J. Arenas, Nonlinear Analysis: Real World Applications 11, 1819–1825 (2010).L. Acedo, G. González-Parra, and A. J. Arenas, Physica A 389, 1151–1157 (2010).G. González-Parra, L. Acedo, and A. J. Arenas, Numerical Algorithms, published online 2013. doi 10.1007/s11075-013-9776-xW. Rindler, Relativity: Special, General and Cosmological, 2nd ed. (Oxford Univ., New York, 2006).G. Arfken, Mathematical Methods for Physicists, 3rd. ed. (Academic, Orlando, Florida, 1985).L. D. Landau and E. M. Lifshitz, The Classical Theory of Fields, 3rd ed. (Pergamon, New York, 1971).O. Costin, “Topological construction of transseries and introduction to generalized Borel summability,” in Analyzable Functions and Applications, Ed. by O. Costin, M. D. Kruskal, and A. Macintyre, Contemp. Math. 373 (Providence, RI, USA: Am. Math. Soc., 2005); arXiv: math/0608309.S. R. Coleman, Phys. Lett. B 70, 59–60 (1977).W. B. Campbell and T. A. Morgan, Phys. Lett. B 84, 87–88 (1979).A. S. Rabinowitch, Int. J. Adv. Math. Sciences 1 (3), 109–121 (2013).A. Feinstein and J. Ibañez, Phys. Rev. D 39 (2), 470–473 (1989)

Ofertas de suplementos múltiplos para tourinhos Nelore na fase de recria em pastagens durante o período da seca: desempenho produtivo e características nutricionais.

Avaliaram-se o desempenho produtivo e as características nutricionais em tourinhos Nelore em fase de recria, não-castrados, recebendo diferentes ofertas de suplementos em pastagem de Brachiaria decumbens, de julho a setembro de 2006. A área foi dividida em cinco piquetes de 2,0 ha, com disponibilidade média de matéria seca (MS) e matéria seca potencialmente digestível (MSpd) de 3,88 e 2,22 t/ha, respectivamente. Foram utilizados 30 bezerros com peso e idade iniciais médios de 230,0 ± 6,14 kg e 8,5 ± 0,18 meses, em delineamento inteiramente casualizado contendo cinco tratamentos: quatro ofertas de suplementos em comparação a mistura mineral (MM). Foram avaliados a MM (60 g/animal) e suplementos múltiplos, fornecidos diariamente nas quantidades de 0,5; 1,0; 1,5 e 2,0 kg/animal para suprir 300 g/dia de PB. Os animais responderam ao uso de suplementos múltiplos, ganhando mais peso (88,72%) e apresentaram maiores níveis séricos de N-ureia (19,95 vs. 9,66) em comparação àqueles que receberam mistura mineral. Os animais sob suplementação apresentaram maiores consumos de MS, MO, EE, FDN, CNF e NDT e esses consumos aumentaram com os níveis de oferta de suplemento. A suplementação aumentou o coeficiente de digestão da maioria das variáveis avaliadas, independentemente do nível de suplemento fornecido. Os níveis mais moderados (0,5 kg) de suplementos múltiplos podem ser fornecidos aos tourinhos em fase de recria durante o período da seca para estimular o consumo de pasto, porém a máxima produção microbiana é obtida com oferta de 1,34 kg de suplemento. As melhores respostas de desempenho e características nutricionais podem ser obtidas com o fornecimento diário de suplemento em níveis de 0,5 a 1,34 kg/animal

Gravitational frequency shifts in transformation acoustics

In metamaterial acoustics, it is conceivable that any type of fine-tuned acoustic properties far beyond those found in nature may be transferred to an appropriate medium. Effective design and engineering of these modern acoustic metadevices poses one of the forefront challenges in this field. As a practical example of a new covariant approach for modelling acoustics on spacetime manifolds, we choose to implement the acoustic analogue of the frequency shift due to gravitational time dilation. In accordance with Einstein's equivalence principle, two different spacetimes, corresponding to uniform acceleration or uniform gravity, are considered. For wave propagation in a uniformly accelerating rigid frame, an acoustic event horizon arises. The discussion includes a detailed numerical analysis for both spacetime geometries. Copyright (c) EPLA, 2013MMT wishes to thank MARKUS SCHOBINGER for an introduction to the SBVP MATLAB solver and acknowledges partial support by the Universidad Politecnica de Valencia (PAID-00-12) and the International Office of the Vienna University of Technology.Tung, MM.; Weinmüller, EB. (2013). Gravitational frequency shifts in transformation acoustics. EPL. 101(5):54006-54011. https://doi.org/10.1209/0295-5075/101/54006S5400654011101

Anomalous accelerations in spacecraft flybys of the Earth

[EN] The flyby anomaly is a persistent riddle in astrodynamics. Orbital analysis in several flybys of the Earth since the Galileo spacecraft flyby of the Earth in 1990 have shown that the asymptotic post-encounter velocity exhibits a difference with the initial velocity that cannot be attributed to conventional effects. To elucidate its origin, we have developed an orbital program for analyzing the trajectory of the spacecraft in the vicinity of the perigee, including both the Sun and the Moon¿s tidal perturbations and the geopotential zonal, tesseral and sectorial harmonics provided by the EGM96 model. The magnitude and direction of the anomalous acceleration acting upon the spacecraft can be estimated from the orbital determination program by comparing with the trajectories fitted to telemetry data as provided by the mission teams. This acceleration amounts to a fraction of a mm/s2 and decays very fast with altitude. 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Current and novel therapeutic opportunities for systemic therapy in biliary cancer

none24Biliary tract cancers (BTCs) are a group of rare and aggressive malignancies that arise in the biliary tree within and outside the liver. Beyond surgical resection, which is beneficial for only a small proportion of patients, current strategies for treating patients with BTCs include chemotherapy, as a single agent or combination regimens, in the adjuvant and palliative setting. Increased characterisation of the molecular landscape of these tumours has facilitated the identification of molecular vulnerabilities, such as IDH mutations and FGFR fusions, that can be exploited for the treatment of BTC patients. Beyond targeted therapies, active research avenues explore the development of novel therapeutics that target the crosstalk between cancer and stroma, the cellular pathways involved in the regulation of cell death, the chemoresistance phenotype and the dysregulation of RNA. In this review, we discuss the therapeutic opportunities currently available in the management of BTC patients, and explore the strategies that can support the implementation of precision oncology in BTCs, including novel molecular targets, liquid biopsies and patient-derived predictive tools.openMarin J.J.G.; Prete M.G.; Lamarca A.; Tavolari S.; Landa-Magdalena A.; Brandi G.; Segatto O.; Vogel A.; Macias R.I.R.; Rodrigues P.M.; Casta A.L.; Mertens J.; Rodrigues C.M.P.; Fernandez-Barrena M.G.; Da Silva Ruivo A.; Marzioni M.; Mentrasti G.; Acedo P.; Munoz-Garrido P.; Cardinale V.; Banales J.M.; Valle J.W.; Bridgewater J.; Braconi C.Marin, J. J. G.; Prete, M. G.; Lamarca, A.; Tavolari, S.; Landa-Magdalena, A.; Brandi, G.; Segatto, O.; Vogel, A.; Macias, R. I. R.; Rodrigues, P. M.; Casta, A. L.; Mertens, J.; Rodrigues, C. M. P.; Fernandez-Barrena, M. G.; Da Silva Ruivo, A.; Marzioni, M.; Mentrasti, G.; Acedo, P.; Munoz-Garrido, P.; Cardinale, V.; Banales, J. M.; Valle, J. W.; Bridgewater, J.; Braconi, C

Receiver design for the REACH global 21-cm signal experiment

We detail the the REACH radiometric system designed to enable measurements of the 21-cm neutral hydrogen line. Included is the radiometer architecture and end-to-end system simulations as well as a discussion of the challenges intrinsic to highly-calibratable system development. Following this, we share laboratory results based on the calculation of noise wave parameters utilising an over-constrained least squares approach demonstrating a calibration RMSE of 80 mK for five hours of integration on a custom-made source with comparable impedance to that of the antenna used in the field. This paper therefore documents the state of the calibrator and data analysis in December 2022 in Cambridge before shipping to South Africa.Comment: 30 pages, 19 figure

Low Radio Frequency Observations and Spectral Modelling of the Remnant of Supernova 1987A

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We present Murchison Widefield Array observations of the supernova remnant (SNR) 1987A between 72 and 230 MHz, representing the lowest frequency observations of the source to date. This large lever arm in frequency space constrains the properties of the circumstellar medium created by the progenitor of SNR 1987A when it was in its red supergiant phase. As of late-2013, the radio spectrum of SNR 1987A between 72 MHz and 8.64 GHz does not show any deviation from a non-thermal power-law with a spectral index of $-0.74 \pm 0.02$. This spectral index is consistent with that derived at higher frequencies, beneath 100 GHz, and with a shock in its adiabatic phase. A spectral turnover due to free-free absorption by the circumstellar medium has to occur below 72 MHz, which places upper limits on the optical depth of $\leq$ 0.1 at a reference frequency of 72 MHz, emission measure of $\lesssim$ 13,000 cm$^{-6}$ pc, and an electron density of $\lesssim$ 110 cm$^{-3}$. This upper limit on the electron density is consistent with the detection of prompt radio emission and models of the X-ray emission from the supernova. The electron density upper limit implies that some hydrodynamic simulations derived a red supergiant mass loss rate that is too high, or a wind velocity that is too low. The mass loss rate of $\sim 5 \times 10^{-6}$ $M_{\odot}$ yr$^{-1}$ and wind velocity of 10 km s$^{-1}$ obtained from optical observations are consistent with our upper limits, predicting a current turnover frequency due to free-free absorption between 5 and 60 MHz.Peer reviewedFinal Published versio