11 resultados para Siglos VIII-XV

em CentAUR: Central Archive University of Reading - UK


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Absolute intensity measurements have been made on the fundamental vibrations of methyl chloride, bromide, and iodide, and their fully deuterated derivatives, by integrating the optical density over the absorption bands. The bands were fully pressure broadened by using up to 80 atmos of foreign gas. Band separations were made graphically. The results are analyzed in terms of the dipole moment derivatives with respect to symmetry coordinates in the molecule, (∂p/∂Si). The data on the different isotopic species are shown to yield consistent results, and this requirement of consistency has also been used as an aid in the analysis. In the E‐class vibrations the signs of the dipole moment derivatives have been determined unambiguously by assuming the permanent dipole to be directed CH3+☒X—.

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Ab initio calculations of the energy have been made at approximately 150 points on the two lowest singlet A' potential energy surfaces of the water molecule, 1A' and 1A', covering structures having D∞h, C∞v, C2v and Cs symmetries. The object was to obtain an ab initio surface of uniform accuracy over the whole three-dimensional coordinate space. Molecular orbitals were constructed from a double zeta plus Rydberg basis, and correlation was introduced by single and double excitations from multiconfiguration states which gave the correct dissociation behaviour. A two-valued analytical potential function has been constructed to fit these ab initio energy calculations. The adiabatic energies are given in our analytical function as the eigenvalues of a 2 2 matrix, whose diagonal elements define two diabatic surfaces. The off-diagonal element goes to zero for those configurations corresponding to surface intersections, so that our adiabatic surface exhibits the correct Σ/II conical intersections for linear configurations, and singlet/triplet intersections of the O + H2 dissociation fragments. The agreement between our analytical surface and experiment has been improved by using empirical diatomic potential curves in place of those derived from ab initio calculations.

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Transreal arithmetic is a total arithmetic that contains real arithmetic, but which has no arithmetical exceptions. It allows the specification of the Universal Perspex Machine which unifies geometry with the Turing Machine. Here we axiomatise the algebraic structure of transreal arithmetic so that it provides a total arithmetic on any appropriate set of numbers. This opens up the possibility of specifying a version of floating-point arithmetic that does not have any arithmetical exceptions and in which every number is a first-class citizen. We find that literal numbers in the axioms are distinct. In other words, the axiomatisation does not require special axioms to force non-triviality. It follows that transreal arithmetic must be defined on a set of numbers that contains{-8,-1,0,1,8,&pphi;} as a proper subset. We note that the axioms have been shown to be consistent by machine proof.

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Studies on princely education rarely focus on the training received by future kings to perform one of their key functions – supervising the finances of the monarchy. Failure to address this issue is all the more surprising than one of the major consequences of Louis XIV’s coronation was to grant the king the direction of finances until the French Revolution, thus raising the issue of the financial education of the prince. Based on a largely unpublished body of primary sources, especially several manuscripts specifically written for the financial education of Louis XV and princes in the XVIIIth century, this article explores the teaching approaches and programme of a highly technical nature that the king’s tutors considered essential to the monarch’s duties.

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This paper reports the results of fieldwork conducted in the 2010 and 2011 DMP field seasons and of analysis of samples collected during these and previous years. Research has involved 1) studying palaeolake sediment outcrops, 2) using ground penetrating radar (GPR) to determine their extent under the Dahān Ubārī, and 3) coring palaeolakes in order to determine their palaeoenvironmental records. Research on these samples is continuing but some initial findings are discussed in this paper. The most extensive palaeolake sediments are found within the al-Mahruqah Formation and were deposited by a giant lake system that developed in the Fazzān Basin during past humid periods. Stratigraphic analysis of Lake Megafazzān sediments suggests two different sedimentary successions, a lake margin succession distinctive for its lacustrine and palaeosol carbonates, and a clastic-dominated, intensely rootleted, basin-centre succession which has terrestrial intervals (aeolian and palaeosols) as well as in the upper parts lacustrine limestones. Both basin margin and basin centre successions are underlain by fluvial deposits. Magnetostratigraphy suggests that the formation may be as old as the mid-Pliocene. After the Lake Megafazzān phase, smaller palaeolakes developed within the basin during subsequent humid periods. One of the largest is found in the Wādī al-Hayāt in the area between Jarma and Ubārī. Similar deposits further west along the Wādī at progressively higher altitudes are interpreted as small lakes and marshes fed by springs issuing from aquifers at the base of the escarpment, last replenished during the Holocene humid phase. Dating of sediments suggests that this was between c. 11 and c. 8 ka. The Wādī ash-Shāţī palaeolake core also provides a Holocene palaeoclimate record that paints a slightly different picture, indicating lake conditions until around 7 ka, whereupon it started oscillating until around 5.5 ka when sedimentation terminates. The reasons for the differences in these records are discussed.

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"Snapshot" of the city of Rome around 1600, with relation to the visual arts, especially the work of artists and architects such as Caravaggio, Annibale Carracci, Rubes, the Cavaliere d'Arpino, Federico Zuccaro, Giacomo della Porta and Carlo Maderno, as well as their patrons (Aldobrandini, Farnese, Giustinani, Mattei, Del Monte).