Fully differential cross sections for four-body scattering processes

While the original concept of the atom can be traced back to the ancient Greeks, current knowledge of the atom is due largely to the study of atomic collisions. The structure of atoms is now fairly well understood, but the understanding of their interactions remains incomplete. In atomic collisions, the particles involved in the collision interact through the Coulomb force, which is known exactly. However, for Coulomb forces, the solution of the Schrödinger equation can only be obtained analytically for two mutually interacting particles. As a result, when more than two particles are involved, theory must resort to approximations. The validity of these approximations is then determined by comparison with experiment. Three new fully quantum-mechanical models that include all relevant two-particle interactions are presented here, and used to study fully differential cross sections (FDCS) of four-body collisions. In particular, this work focuses on electron-impact excitation-ionization of helium, as well as single charge transfer, transfer-excitation, and double charge transfer in proton + helium collisions. The calculations required for this work result in nine-dimensional integrals that are performed numerically. For excitation-ionization, the projectile-ejected electron interaction is found to be important in correctly predicting the shape of the FDCS. However, the projectile-atom and projectile-ion interactions play a much smaller role in this process. For single charge transfer and transfer-excitation, the current model does a reasonable job of predicting the shape and magnitude of experiment. However, for double charge transfer, the theoretical results overestimate experiment by several orders of magnitude. For all of the charge transfer collisions, calculations show that the interaction of the electrons within the target atom has little effect on the FDCS --Abstract, page iii

Stellar populations in the Canis Major over-density

We performed a photometric multicolor survey of the core of the Canis Major over-density at l 244, -8.0, reaching V = 22 and covering 0.3 x 1 degree. The main aim is to unravel the complex mixture of stellar populations toward this Galactic direction, where in the recent past important signatures of an accretion event have been claimed to be detected. While our previous investigations were based on disjointed pointings aimed at revealing the large scale structure of the third Galactic Quadrant, we now focus on a complete coverage of a smaller field centered on the Canis Major over-density. A large wave-length baseline, in the UBVRI bands, allows us to build up a suite of colour colour and colour magnitude diagrams, providing a much better diagnostic tool to disentangle the stellar populations of the region. In fact, the simple use of one colour magnitude diagram, widely employed in all the previous studies defending the existence of the Canis Major galaxy, does not allow one to separate the effects of the different parameters (reddening, age, metallicity, and distance) involved in the interpretation of data, forcing to rely on heavy modeling. In agreement with our previous studies in the same general region of the Milky Way, we recognize a young stellar population compatible with the expected structure and extension of the Local (Orion) and Outer (Norma-Cygnus) spiral arms in the Third Galactic Quadrant. Moreover we interpret the conspicuous intermediate-age metal poor population as belonging to the Galactic thick disk, distorted by the effect of strong disk warping at this latitude, and to the Galactic halo.Comment: 9 pages, 12 eps figures (some of them somewhat degraded in resolution), accepted for publication in MNRA

Rothmund-Thomson syndrome: Insights from new patients on the genetic variability underpinning clinical presentation and cancer outcome

Biallelic mutations in RECQL4 gene, a caretaker of the genome, cause Rothmund-Thomson type-II syndrome (RTS-II) and confer increased cancer risk if they damage the helicase domain. We describe five families exemplifying clinical and allelic heterogeneity of RTS-II, and report the effect of pathogenic RECQL4 variants by in silico predictions and transcripts analyses. Complete phenotype of patients #39 and #42 whose affected siblings developed osteosarcoma correlates with their c.[1048_1049del], c.[1878+32_1878+55del] and c.[1568G>C;1573delT], c.[3021_3022del] variants which damage the helicase domain. Literature survey highlights enrichment of these variants affecting the helicase domain in patients with cancer outcome raising the issue of strict oncological surveillance. Conversely, patients #29 and #19 have a mild phenotype and carry, respectively, the unreported homozygous c.3265G>T and c.3054A>G variants, both sparing the helicase domain. Finally, despite matching several criteria for RTS clinical diagnosis, patient #38 is heterozygous for c.2412_2414del, no pathogenic CNVs out of those evidenced by high-resolution CGH-array, emerged as contributors to her phenotype

Avaliação de genótipos de grão de bico em cultivo de sequeiro nas condições de cerrado.

O presente trabalho teve o objetivo de estimar o potencial de cultivo de grão de bico quando submetido a regime de baixa umidade no solo (sequeiro) e identificar genótipos com melhores características morfoagronômicas e de rendimento

Chemistry of functionalised macrocycles

The work reported in this thesis is divided into two distinct areas. The first involves the synthesis of monoaza- and diaza-[12]-ring macrocycles, with differing side-arm N-substituents. The twelve-membered macrocycles possess a convenient ring-size for exploring the stability and selectivity of complexation of small cations, in particular those from groups IA and IIA. Amide substituents on nitrogen were expected to function as effective σ-donors to cations with high charge density (e.g. Li (^+), Ca (^2)(^+)), because of their high ground state dipole moments. The effect of the length of the side-arms attached to nitrogen on the complexation has also been studied. Complexation behaviour has been probed using (^13)C NMR spectroscopy, titration calorimetry, and fast-atom bombardment mass spectroscopy. Copper (II) complexes of three of the [12]-ring cycles have also been characterised by X-ray crystallographic analysis. The second area involves the study of a series of macrocyclic ligands capable of forming homo- and hetero-dinuclear complexes. In particular, ligands containing the pyridyl-dithio (PyS(_2)) binding unit and a polyether chain linking the two sulphur atoms have been examined. The three binding atoms of each PyS (_2) group define three corners of a fairly rigid square planar environment which favours the formation of square planar d(^8) complexes. Accordingly, complexation with rhodium (I) [and (III)], palladium (II), and platinum (II) has been investigated: the structural properties of these complexes have been determined by the use of FT NMR and X-ray crystallography