The direct observation of gravitational waves will provide a unique tool for probing the dynamical properties of highly compact astrophysical objects, mapping ultra-relativistic regions of space-time, and testing Einstein's general theory of relativity. LISA (Laser Interferometer Space Antenna), a joint NASA-ESA mission to be launched in the next decade, will perform these scientific tasks by detecting and studying low-frequency cosmic gravitational waves through their influence on the phases of six modulated laser beams exchanged between three remote spacecraft. By directly measuring the polarization components of the waves LISA will detect, we will be able to test Einstein's theory of relativity with good sensitivity. Since a gravitational wave signal predicted by the most general relativistic metric theory of gravity accounts for six polarization modes (the usual two Einstein's tensor polarizations as well as two vector and two scalar wave components), we have derived the LISA Time-Delay Interferometric responses and estimated their sensitivities to vectorand scalar-type waves. We find that (i) at frequencies larger then roughly the inverse of the oneway light time (≈ 6 × 10 −2 Hz.) LISA is more than ten times sensitive to scalar-longitudinal and vector signals than to tensor and scalar-transverse waves, and (ii) in the low part of its frequency band is equally sensitive to tensor and vector waves and somewhat less sensitive to scalar signals.

Pulsar timing experiments aimed at the detection of gravitational radiation have been performed for decades now. With the forthcoming construction of large arrays capable of tracking multiple millisecond pulsars, it is very likely we will be able to make the first detection of gravitational radiation in the nano-Hertz band, and test Einstein's theory of relativity by measuring the polarization components of the detected signals. Since a gravitational wave predicted by the most general relativistic metric theory of gravity accounts for six polarization modes (the usual two Einstein's tensor polarizations as well as two vector and two scalar wave components), we have estimated the single-antenna sensitivities to these six polarizations. We find pulsar timing experiments to be significantly more sensitive, over their entire observational frequency band (≈ 10 −9 − 10 −6 Hz), to scalar-longitudinal and vector waves than to scalar-transverse and tensor waves. At 10 −7 Hz and with pulsars at a distance of 1 kpc, for instance, we estimate an average sensitivity to scalar-longitudinal waves that is more than two orders of magnitude better than the sensitivity to tensor waves. Our results imply that a direct detection of gravitational radiation by pulsar timing will result into a test of the theory of general relativity that is more stringent than that based on monitoring the decay of the orbital period of a binary system. 95.36.+x, 95.30.Sf

Este artigo relata as ações de discentes de um curso de graduação em Engenharia Ambiental sobre a temática "resíduos sólidos", em uma escola de ensino básico. Com o desenvolvimento dessas atividades, objetivou-se capacitar os futuros engenheiros ambientais, considerando os aspectos éticos e humanísticos de sua formação, para o atendimento das demandas da sociedade. Professores e discentes do Departamento de Engenharia Ambiental delinearam aulas teóricas e práticas e realizaram um curso sobre o tema para alunos dos 6º e 7º anos do Ensino Fundamental. Questionários iniciais e finais foram aplicados aos participantes para avaliar os conceitos sobre o tema, verificando-se que, após a realização do curso, 73% e 25% dos participantes passaram a utilizar corretamente os conceitos ligados, respectivamente, a "coleta seletiva" e "problemas ambientais", relacionados à geração dos resíduos sólidos. Com o desenvolvimento do projeto, os alunos de graduação foram expostos à realidade da problemática da geração de resíduos sólidos e do desafio do processo de conscientização referentes às questões ambientais observadas no país.