Tracing the journey of the sun and the solar siblings through the Milky Way

  This thesis is focused on studying the motion of the Sun and the Solar siblings through the Galaxy. The Solar siblings are stars that were born with the Sun in the same molecular cloud 4.6 Gyr ago. In the first part of the thesis, we present an efficient method to calculate the evolution of small systems embedded in larger systems. Generalizations of this method are used to calculate the motion of the Sun and the Solar siblings in an analytical potential containing a central bar and spiral arms. By integrating the orbit of the Sun backwards in time, we determine its birth radius and the amount of radial migration experienced by our star. The birth radius of the Sun is used to investigate the evolution and disruption of the Sun's birth cluster. Depending on the Galaxy model parameters, the present-day phase-space distribution of the Solar siblings might be quite different. We used these data to predict the regions in the Galaxy where it will be more likely to search for Solar siblings in the future. Finally, we compute the stellar encounters experienced by the Sun along its orbit and their role on the stability of the outer Solar System.  Gaia Research for European Astronomy Training (GREAT-ITN) networkSterrewacht - OU

Cyanolipids from Sapindus saponaria L. seeds oil

The chemical composition of the oil extracted from the seeds of Sapindus saponaria L., (Sapindaceae), was investigated. Cyanolipids constituted 5% hexane extract of the seeds, whereas triacylglycerols (TAG) accounted for 90%. The oil contains type III cyanolipids (CL) 1-cyano-2-hydroxymethylprop-1-en-3-ol-diesters. Structural investigation of the oil components was accomplished by chemical, chromatographic (TLC, CC, GC-MS), and spectroscopic (IR, NMR) means. GC-MS analysis showed that fatty acids were dominant in the CL components of the oil from S. saponaria L., with cis-11-eicosenoic acid, cis-11-octadecenoic acid and eicosanoic acid as the only esterified fatty acyl chains respectively. This being the first report of this kind of natural products (CL), located in the seeds of this plant

Tylopilus dunensis (Boletaceae, Basidiomycota): notes on morphological, phylogenetical and distributional aspects

Tylopilus is a worldwide distributed genus of boletes with about 100 known taxa, of which at least 16 are from Brazil and Guyana. Tylopilus dunensis, a species originally described from sand dune habitats in the state of Rio Grande do Norte in northeastern Brazil, has now been recovered in a ‘tabuleiro’ (i.e., tableland forest) from Paraíba. The main phenetic features of this still poorly known species are the orange to orange-ochraceous pileus with yellowish brown margins, unchanging pileus context, the pale cream hymenophore with wide pores, the yellowish stipe, the small and narrow basidiospores, and the long and frequent dextrinoid pseudocystidioid pleurocystidia. After the discovery of the phylloporoid tube trama in our specimens, we emended tube trama type of T. dunensis

Evaluation Of The Risk Of A Stripping Perforation With Gates-glidden Drills: Serial Versus Crown-down Sequences

The aim of this study was to evaluatte the remaining dentine/cementum thickness using Gates-Glidden burs in serial and crown-down sequences and to observe which of the two sequences is the safest for preparing mesial roots of molars. Thirty-six left and. right human mandibular first molars were selected. Standard access cavities were made and initially explored with Flexofiles sizes 10 and 15 until the tip was visible at the apex. The teeth were embedded in a muffle speqially developed for this study using a PVC tube with two parallel metal rods An its lid. Each tooth-block was sectioned 3 mm apically to the furcation using a low-speed saw with a diamond disc. The tooth-block was examined under a microscope and an initial image was captured by a digital video system with 8 X and 12 X magnifications. Finally, the tooth-blocks were reassembled in the muffle so that the canals could be instrumented. After instrumentation the area of each mesial canal as well as the smallest distance to the root furcation were measured again. The mesio-buccal canals (crown-down order) and the mesio-lingual canals (serial sequence) presented an average area of 0.46 ± 0.16 mm2 and 0.88 ± 0.27 mm2 (P < 0.01), respectively. The mean values of the smallest distance to the furcation for the mesio-buccal and mesio-lingual canals were 0.66 ± 0.19 mm and 0.39 ± 0.13 mm (P < 0.01), respectively. The remaining dentine/cementum thickness using Gates-Glidden burs was greater in the crown-down sequence than in the serial sequence.2211824Grossman, L., A brief history of endodontics (1982) J Endod, 8 (1), p. 538Mullaney TP. Instrumentation of finely curved canals. Dent Clin North Am. l979;23(4):575-92Taintor, J.F., Use of the gates glidden bur in endodontics (1978) J Nebr Dent Assoc, 54 (3), pp. 10-12Weine, F.S., Kelly, R.E., Lio, P.J., The effect of preparation procedures on original canal shape and on apical foramen shape (1975) J Endod, 1 (8), pp. 255-262Abou-Rass, M., Frank, A.L., Glick, D.H., The anticurvature filing method to prepare the curved root canal (1980) J Am Dent Assoc, 101 (5), pp. 792-794Cunningham, C.J., Senia, S.E., A three-dimensional study of canal curvatures in the mesial roots of mandibular molars (1992) J Endod, 18 (6), pp. 294-300Coutinho-Filho.T, De-Deus G, Guimarães T, Gurgel-Filho ED, Maniglia-Ferreira C. A computer evaluation of the dentin remaining after cervical preparation in curved canals: Gatesglidden drills vs. orifice shaper. Braz J Oral Sci. 2002;1(3):116-20Lim, S.S., Stock, C.J., The risk of perforation in the curved canal: Anticurvature filing compared with the step-back technique (1987) Int Endod J, 20 (1), pp. 33-39Isom, T.L., Marshall, J.G., Baumgartner, J.C., Evaluation of root thickness in curved canals after flaring (1995) J Endod, 21 (7), pp. 368-371Gluskin, A.H., Brown, D.C., Buchanan, L.S., A reconstructed computerized tomographic comparison of Ni-Ti rotary GT files versus traditional instruments in canals shaped by novice operators (2001) Int Endod J, 34 (6), pp. 476-484Schilder, H., Cleaning and shaping the root canal (1974) Dent Clin North Am, 18 (2), pp. 269-296Bramante, C.M., Berbet, A., Borges, R.P., A methodology for evaluation of root canal instrumentation (1987) J Endod, 13 (5), pp. 243-245Bower, R.C., Furcation morphology relative to periodontal treatment. Furcation entrance architecture (1979) J Periodontol, 50 (1), pp. 23-27Kessler, J.R., Peters, D.D., Lorton, L., Comparison of the relative risk of molar root perforations using various endodontic instrumentation techniques (1983) J Endod, 9 (10), pp. 439-447McCann, J.T., Keller, D.L., LaBounty, G.L., A modification of the muffle model system to study root canal morphology (1990) J Endod, 16 (3), pp. 114-115Pilo, R., Corcino, G., Tamse, A., Residual dentin thickness in mandibular premolars prepared with hand and rotatory instruments (1998) J Endod, 24 (6), pp. 401-404Torabinejad, M., Rotstein, L., Stabholz, A., Effect of preflaring on tactile detection of the apical constriction (1995) J Endod, 21 (2), pp. 92-94West JD, Roane JB. Limpeza e modelagem do sistema de canais radiculares. In: Cohen S, Burns RC. Caminhos da polpa. 7th ed. Rio de Janeiro: Guanabara Koogan2000. p. 206-36Abou-Rass, M., Jastrab, R.J., The use of rotary instruments as auxiliary aids to root canal preparation of molars (1982) J Endod, 8 (2), pp. 78-7

Computation of initial conditions for a thin disc as an extension of Dehnen algorithm

Galaxie

Radial migration of the Sun in the Milky Way: a statistical study

Computational astrophysic

The rate of stellar encounters along a migrating orbit of the Sun

GalaxiesComputational astrophysic

Is the Sgr dSph a dark matter dominated system?

We study the evolution of possible progenitors of Sgr dSph}using several numerical N-body simulations of different dwarf spheroidal galaxies both with and without dark matter, as they orbit the Milky Way. The barionic and dark components of the dwarfs were made obeying a Plummer and NFW potentials of one million particles respectively. The Milky Way was modeled like a tree-component rigid potential and the simulations were performed using a modified Gadget-2 code. We found that none of the simulated galaxies without dark matter reproduced the physical properties observed in Sgr dSph, suggesting that, at the beginning of its evolution, Sgr dSph might have been immersed in a dark matter halo. The simulations of progenitors immersed in dark matter halos suggest that Sgr dSph at its beginning might have been an extended system, i.e. its Plummer radius could have had a value approximated to 1.2 kpc or higher; furthermore, this galaxy could have been immersed in a dark halo with a mass higher than 10^8 solar masses. These results are important for the construction of a model of the formation of Sgr dSph.Comment: 13 pages, 6 figures, New Astronomy - accepte