1,529 research outputs found

    Primordial molecular clouds

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    It is now well known that a primordial chemistry, involving light elements produced during the nucleosynthesis period, might develop during the hydrogen post-recombination era. In particular, molecular ions and primordial molecules such as H2, HD and LiH will be produced. We summarize this primordial chemistry after the recombination epoch, and then present a simple gravitational collapse model of a cloud. The potentiality of fragmentation of this collapsing protoclouds through the thermal instability is also discussed. We suggest that this study could also be extended to the CO molecule, because the carbon reservoir molecule CO has already been observed in high redshifts objects.Comment: 12 pages, 1 figures, Invited Talk at 3K Cosmology Conference-Roma October 9

    Big Bang Nucleosynthesis, Cosmic Microwave Background Anisotropies and Dark Energy

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    Over the last decade, cosmological observations have attained a level of precision which allows for very detailed comparison with theoretical predictions. We are beginning to learn the answers to some fundamental questions, using information contained in Cosmic Microwave Background Anisotropy (CMBA) data. In this talk, we briefly review some studies of the current and prospected constraints imposed by CMBA measurements on the neutrino physics and on the dark energy. As it was already announced by Scott (1999), we present some possible "new physics" from the Cosmic Microwave Background.Comment: 11 pages, 5 figures, Talk given at 2K1BC Workshop, July 9-12, 2001, Breuil-Cervinia (Italy

    Primordial molecules at millimeter wavelengths

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    Chemistry plays a particular role in astrophysics. After atomic hydrogen, helium and their ions, the Universe probably contains more mass in molecules than in any other species. Molecule formation in the early, pre-galactic Universe may have had much to do with the formation of galaxies themselves. In this context the possible interaction between primordial molecules and photons of the Cosmic Microwave Background is very important through the theoretical perspectives and constraints which could give some information on the theory of the large scale structure formation. In this paper we recall the more recent progresses on the chemistry of the early Universe, and describe the importance of molecules in the formation phase of proto objects. A special attention is done concerning the {\it case of LiH.Comment: 8 pages, Talk given at 2K1BC Workshop, July 9-12, 2001, Breuil-Cervinia (Italy

    The Problem of Inertia in Friedmann Universes

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    In this paper we study the origin of inertia in a curved spacetime, particularly the spatially flat, open and closed Friedmann universes. This is done using Sciama's law of inertial induction, which is based on Mach's principle, and expresses the analogy between the retarded far fields of electrodynamics and those of gravitation. After obtaining covariant expressions for electromagnetic fields due to an accelerating point charge in Friedmann models, we adopt Sciama's law to obtain the inertial force on an accelerating mass mm by integrating over the contributions from all the matter in the universe. The resulting inertial force has the form F=−kmaF = -kma, where k<1k < 1 depends on the choice of the cosmological parameters such as ΩM\Omega_{M}, ΩΛ\Omega_{\Lambda}, and ΩR\Omega_{R} and is also red-shift dependent.Comment: 10 page

    Dismenorrea in donne lavoratrici dell'industria

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    La dismenorrea è una delle più comuni indisposizioni nelle donne. La frequenza varia in differenti lavori, probabilmente ciò è dovuto alla differenza nei gruppi di popolazione studiati. In alcune industrie Norvegesi, con molto personale femminile, l’inabilità periodica al lavoro dovuto ai fastidi mestruali è stato un problema di una certa importanza e la domanda è sorta nel caso in cui l’assenza è medicalmente giustificata nella visione di un moderno trattamento ormonale. Per avvicinarci al problema abbiamo pianificato di esaminare l’evento dei fastidi mestruali, particolarmente la dismenorrea, tra il personale femminile in alcune industrie Italiane in quello che appariva essere un problema. I soggetti esaminati erano impiegati di una compagnia elettrica-tecnica e di una industria tessile. Un questionario preparato da una infermiera dell’industria, è stato compilato da donne in età mestruale che erano state visitate per esami medici periodici e di pre-assunzione tra il 2002-2003. Ogni donna assistita soffriva di dolore, e quando tutti i sintomi erano considerati il 61% aveva mensilmente disturbi che ovviamente riducevano la loro capacità sul lavoro. Visto che il 9% delle donne assumevano estroprogestinici, che riducevano o eliminavano la dismenorrea, la vera prevalenza potrebbe essere leggermente superiore. Circa il 30% delle donne erano confinate a letto. Circa il 30% si assentava dal lavoro, il che illustra la grandezza del problema sia medico che economico
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