Collision-Dependent Atom Tunnelling Rate in Bose-Einstein Condensates

We show that the interaction (cross-collision) between atoms trapped in distinct sites of a double-well potential can significantly increase the atom tunneling rate for special trap configurations leading to an effective linear Rabi regime of population oscillation between the trap wells. The inclusion of cross-collisional effects significantly extends the validity of the two-mode model approach allowing it to be alternatively employed to explain the recently observed increase of tunneling rates due to nonlinear interactions.Comment: 4 pages, 2 figures. Replaced with improved versio

Optimal Conditions for Atomic Homodyne Detection on Bose-Einstein Condensates

The dynamics of a two-mode Bose-Einstein condensate trapped in a double-well potential results approximately in an effective Rabi oscillation regime of exchange of population between both wells for sufficiently strong overlap between the modes functions. Facing this system as a temporal atomic beam splitter we show that this regime is optimal for a nondestructive atom-number measurement allowing an atomic homodyne detection, thus yielding indirect relative phase information about one of the two-mode condensates.Comment: 9 pages, 5 figure

On the nature of the spin-polarized hole states in a quasi-two-dimensional GaMnAs ferromagnetic layer

A self-consistent calculation of the density of states and the spectral density function is performed in a two-dimensional spin-polarized hole system based on a multiple-scattering approximation. Using parameters corresponding to GaMnAs thin layers, a wide range of Mn concentrations and hole densities have been explored to understand the nature, localized or extended, of the spin-polarized holes at the Fermi level for several values of the average magnetization of the Mn ystem. We show that, for a certain interval of Mn and hole densities, an increase on the magnetic order of the Mn ions come together with a change of the nature of the states at the Fermi level. This fact provides a delocalization of spin-polarized extended states anti-aligned to the average Mn magnetization, and a higher spin-polarization of the hole gas. These results are consistent with the occurrence of ferromagnetism with relatively high transition temperatures observed in some thin film samples and multilayered structures of this material.Comment: 3 page

Spin-polarized transport in ferromagnetic multilayered semiconductor nanostructures

The occurrence of inhomogeneous spin-density distribution in multilayered ferromagnetic diluted magnetic semiconductor nanostructures leads to strong dependence of the spin-polarized transport properties on these systems. The spin-dependent mobility, conductivity and resistivity in (Ga,Mn)As/GaAs,(Ga,Mn)N/GaN, and (Si,Mn)/Si multilayers are calculated as a function of temperature, scaled by the average magnetization of the diluted magnetic semiconductor layers. An increase of the resistivity near the transition temperature is obtained. We observed that the spin-polarized transport properties changes strongly among the three materials.Comment: 3 pages, 4 figure

Magnetic ordering in GaAlAs:Mn double well structure

The magnetic order in the diluted magnetic semiconductor barrier of double AlAs/GaAs: Mn quantum well structures is investigated by Monte Carlo simulations. A confinement adapted RKKY mechanism is implemented for indirect exchange between Mn ions mediated by holes. It is shown that, depending on the barrier width and the hole concentration a ferromagnetic or a spin-glass order can be established.Comment: 3 figure

Theodosius Dobzhansky And The Development Of Genetics In Brazil

[No abstract available]263387395de Barros, R., Aberrações cromosômicas em Drosophila mercatorum pararepleta. I. Aneuplóides expontâneos (1949) Rev. Bras. Biol., 9 (3), pp. 365-376de Barros, R., Aberrações cromosômicas em Drosophila mercatorum pararepleta. II. Uma longa duplicação expontânea adjacente e invertida (1949) Rev. Bras. Biol., 9 (4), pp. 463-466de Barros, R., Um caso de alteração na proporção entre os sexos, em Drosophila mercatorum pararepleta (1949) Cienc. Cult., 1 (3), pp. 107-110de Barros, R., A new species of the genus Drosophila, with discussion about speciation in the mercatorum sub-group (1950) Rev. Bras. Biol., 10 (3), pp. 265-278Birch, L.C., Battaglia, B., The abundance of Drosophila willistoni in relation to food in natural populations (1957) Ecology, 38 (1), pp. 165-166Birch, L.C., Battaglia, B., Selection in Drosophila willistoni in relation to food (1957) Evolution Int. J. Org. Evolution, 11, pp. 94-105Breuer, M.E., Pavan, C., Genitália masculina de Drosophila (Diptera) do grupo annulimana (1950) Rev. Bras. Biol., 10 (4), pp. 469-488Breuer, M.E., Pavan, C., Genitália masculina de Drosophila (Diptera) do grupo dreyfusi (1954) Rev. Bras. Biol., 14 (4), pp. 465-475Burla, H., Pavan, C., The calloptera group of species (1953) Rev. Bras. Biol., 13 (4), pp. 291-314Burla, H., da Cunha, A.B., Cordeiro, A.R., Dobzhansky, Th., Malogolowkin, C., Pavan, C., The willistoni group of sibling species of Drosophila (1949) Evolution Int. J. Org. Evolution, 3 (4), pp. 300-314Burla, H., da Cunha, A.B., Cavalcanti, A.G.L., Dobzhansky, Th., Pavan, C., Population density and dispersal rates in Brazilian Drosophila willistoni (1950) Ecology, 31 (3), pp. 393-404Carson, H.L., Interfertile sibling species in the willistoni group of Drosophila (1954) Evolution Int. J. Org. Evolution, 8, pp. 148-165da Cunha, A.B., Polymorphism in natural populations of a species of Drosophila (1946) J. Hered., 37 (8), pp. 253-257da Cunha, A.B., Genetic analysis of the polymorphism of color pattern in Drosophila polymorpha (1949) Evolution Int. J. Org. Evolution, 3 (3), pp. 239-251da Cunha, A.B., Contribuição ao estudo do polimorfismo (1951) Bol. Fac. Filos. Cienc. Letras Univ. São Paulo, 131, pp. 1-58. , (Biol Geral 9)da Cunha, A.B., Modification of the adaptive values of chromosomal types in Drosophila pseudoobscura by nutritional variables (1951) Evolution Int. J. Org. Evolution, 5 (4), pp. 395-404da Cunha, A.B., A further analysis of the polymorphism of Drosophila polymorpha (1953) Nature, 171, p. 887da Cunha, A.B., Chromosomal inversions with sex-limited effects (1953) Nature, 172, pp. 815-816da Cunha, A.B., Chromosomal polymorphism in the Diptera (1955) Adv. Genet., 7, pp. 93-138da Cunha, A.B., Sobre duas raças de Drosophila neocardini Streisinger (Drosophilidae, Diptera) (1955) Rev. Bras. Biol., 15 (1), pp. 117-125da Cunha, A.B., Adaptation of carriers of different chromosomal types in Drosophila willistoni to a variety of environments (1956) Rev. Bras. Biol., 16, pp. 263-272da Cunha, A.B., Differential viability favoring inversion heterozygotes in Drosophila willistoni (1956) Evolution Int. J. Org. Evolution, 10 (3), pp. 231-234da Cunha, A.B., Contribuição ao estudo da adaptação das populações de Drosophila (Diptera) a diferentes levedos (1957) Bol. Fac. Filos. Cienc. Letras Univ. São Paulo, 220, pp. 1-60. , (Biol Geral 10)da Cunha, A.B., Chromosomal variation and adaptation in insects (1960) Annu. Rev. Entomol., 5, pp. 85-110da Cunha, A.B., Maintenance of the lethal and detrimental genes in natural populations (1968) Proceedings 12th International Congress of Genetics, Tokyo, 2, pp. 162-164da Cunha, A.B., Dobzhansky, Th., A further study of chromosomal polymorphism in Drosophila willistoni and its relation to the environment (1954) Evolution Int. J. Org. Evolution, 8 (2), pp. 119-134da Cunha, A.B., Kerr, W.E., A genetical hypothesis to explain sex-determination by arrhenotokous parthenogenesis (1956) Forma et Functio., 1, pp. 33-36da Cunha, A.B., Pavan, C., O futuro biológico do homem (1967) An. Acad. Bras. Cienc., 39 (SUPPL.), pp. 7-15da Cunha, A.B., Burla, H., Dobzhansky, Th., Adaptive chromosomal polymorphism in Drosophila willistoni (1950) Evolution Int. J. Org. Evolution, 4 (3), pp. 212-235da Cunha, A.B., Dobzhansky, Th., Sokoloff, A., On food preferences of sympatric species of Drosophila (1951) Evolution Int. J. Org. Evolution, 5 (2), pp. 91-101da Cunha, A.B., Brncic, D., Salzano, F.M., A comparative study of chromosomal polymorphism in certain South-American species of Drosophila (1953) Heredity, 7 (2), pp. 193-202da Cunha, A.B., El-Tabey Shehata, A., de Oliveira, W., A study of the diets and nutritional preferences of tropical species of Drosophila (1957) Ecology, 38 (1), pp. 98-106da Cunha, A.B., Dobzhansky, Th., Pavlovsky, O., Spassky, B., Genetics of natural populations XXVIII. Supplementary data on the chromosomal polymorphism in Drosophila willistoni and its relation to the environment (1959) Evolution Int. J. Org. Evolution, 13, pp. 389-404da Cunha, A.B., de Toledo, J.S., Pavan, C., de Souza, H.L., Melara, H.E., Gabrusewycz, N., Gama, M.R., de Mello, L.C., A comparative analysis of the effects of natural and of radiation-induced lethals in heterozygous individuals and their frequencies in natural populations of Drosophila willistoni (1959) Progress in Nuclear Energy, Series VI, Biological Sciences, 2, pp. 359-363. , Also in Proceedings of the Second United Nations International Conference on the Peaceful Uses of Atomic Energy 22:330-332da Cunha, A.B., de Toledo, J.S., Pavan, C., de Souza, H.M.L., Gabrusewycz, N., Gama, M.R., Análise comparativa dos comportamentos de gens letais naturais e de gens letais induzidos por radiação em populações naturais (1960), Atas do II Simpósio Interamericano para Usos Pacíficos da Energia Nuclear, Buenos Airesda Cunha, A.B., de Magalhães, L.E., de Toledo, J.S., Toledo Filho, S.A., de Souza, H.M.L., On the origin of new lethal chromosomes and its rate in laboratory populations of Drosophila willistoni (1966) Mutat. Res., 3, p. 460. , 458da Cunha, A.B., França, Z.M., Gonçalves, A.M.A., Hitelman, A., Garrido, M.C., Chromosomal diseases in Drosophila willistoni Sturtevant (1967) Rev. Bras. Biol., 27, pp. 113-124Dobzhansky, Th., da Cunha, A.B., Differentiation of nutritional preferences in Brazilian Drosophila (1955) Ecology, 36, pp. 34-39Dobzhansky, Th., Dreyfus, A., Chromosomal aberrations in Brazilian Drosophila ananassae (1943) Proc. Natl. Acad. Sci. USA, 29 (10), pp. 301-305Dobzhansky, Th., Pavan, C., Studies on Brazilian species of Drosophila (1943) Bol. Fac. Filos. Cienc. Letras Univ. São Paulo, 36, pp. 7-72. , (Biol Geral 4 + 7 platesDobzhansky, Th., Pavan, C., Chromosome complements of some South-Brazilian species of Drosophila (1943) Proc. Natl. Acad. Sci. USA, 29 (11), pp. 368-375Dobzhansky, Th., Pavan, C., Local and seasonal variations in relative frequencies of species of Drosophila in Brazil (1950) J. Anim. Ecol., 19 (1), pp. 1-14Dobzhansky, Th., Burla, H., da Cunha, A.B., A comparative study of chromosomal polymorphism in sibling species of the willistoni group of Drosophila (1950) Am. Nat., 89, pp. 229-246Dreyfus, A., Analysis of sexual isolation between Drosophila paranaensis and D. pararepleta (1951) Proc. of the Eighth International Congress of Genetics, (SUPPL.), pp. 564-565. , HereditasDreyfus, A., de Barros, R., Mutations chromosomiques chez les hybrides de Drosophila mercatorum pararepleta x D. paranaensis (1948) São Paulo Médico, 1, pp. 11-18Dreyfus, A., de Barros, R., Sex-ratio chez certains hybrides interspécifiques de Drosophila et son interprétation par l'analyse des chromosomes salivaires (1949), pp. 94-104. , Symposium sui fattori ecologici e genetici della speciazione negli animali. Suppl. A "La Ricerca Scientifica"França, Z.M., da Cunha, A.B., Crossing-over between heterozygous inversions and its relation with polymorphism in Drosophila willistoni (1968) Rev. Bras. Biol., 28, pp. 495-497França, Z.M., da Cunha, A.B., Garrido, M.C., Recombination in Drosophila willistoni (1968) Heredity, 23, pp. 199-204Freire-Maia, N., Sobre os cromossomos de Drosophila montium (1947) Bol. Fac. Filos. Ciene Letras Univ. São Paulo, 86, pp. 3-19. , (Biol Geral 7)Freire-Maia, N., Balanced polymorphism in Drosophila montium (1949) Evolution Int. J. Org. Evolution, 3, p. 98Frydenberg, O., Two new species of Drosophila from Peru (Drosophilidae, Diptera) (1956) Rev. Bras. Entomol., 6, pp. 57-64Ives, P.T., The genetic structure of American populations of Drosophila melanogaster (1945) Genetics, 30, pp. 167-196de Magalhães, L.E., Description of four new species of the saltans group of Drosophila (Diptera) (1956) Rev. Bras. Biol., 16 (3), pp. 273-280de Magalhães, L.E., Björnberg, A.J.S., Estudo da genitália masculina de Drosophila (Diptera) do grupo saltans (Diptera) (1957) Rev. Bras. Biol., 17 (4), pp. 435-450de Magalhães, L.E., de Toledo, J.S., da Cunha, A.B., The nature of lethals in Drosophila willistoni (1965) Genetics, 53, pp. 559-608de Magalhães, L.E., da Cunha, A.B., de Toledo, J.S., Toledo Filho, S.A., de Souza, H.L., Targa, H.J., Setzer, V., Pavan, C., On lethals and their suppressors in experimental populations of Drosophila willistoni (1965) Mutat. Res., 2, pp. 45-54Patterson, J.T., Pavan, C., Drosophila fulvimacula flavorepleta subsp. nov (1952) Univ. Tex. Publ., pp. 114-128. , Patterson JT (ed) A pair of allopatric subspecies belonging to the repleta species group 5204Pavan, C., Chromosomal variations in Drosophila nebulosa (1946) Genetics, 31, pp. 546-557Pavan, C., Two types of heterochromatin in Drosophila nebulosa (1946) Proc. Natl. Acad. Sci. USA, 32 (5), pp. 137-145Pavan, C., Espécies brasileiras de Drosophila II (1950) Bol. Fac. Filos. Cienc. Letras Univ. São Paulo, 111, pp. 1-37. , (Biol Geral 8)Pavan, C., Relações entre populações naturais de Drosophila e o meio ambiente (1952), Cathedra Thesis, Universidade de São Paulo, São PauloPavan, C., Breuer, M.E., Two new species of Drosophila (Diptera) of the dreyfusi group (Diptera) (1954) Rev. Bras. Biol., 14 (4), pp. 459-463Pavan, C., da Cunha, A.B., Espécies brasileiras de Drosophila (1947) Bol. Fac. Filos. Cienc. Letras Univ. São Paulo, 86, pp. 20-64. , (Biol Geral 7)Pavan, C., da Cunha, A.B., Os efeitos genéticos das radiações (1967) An. Acad. Bras. Cienc., 39 (SUPPL.), pp. 115-128Pavan, C., Knapp, E.P., The genetic population structure of Brazilian Drosophila willistoni (1954) Evolution Int. J. Org. Evolution, 8 (4), pp. 303-313Pavan, C., Nacrur, J., Duas novas espécies de Drosophila (Diptera) do grupo annulimana (1950) Dusenia, 1 (5), pp. 263-274Pavan, C., Cordeiro, A.R., Dobzhansky, N., Dobzhansky, Th., Malogolowkin, C., Spassky, B., Wedel, M., Concealed genetic variability in Brazilian populations of Drosophila willistoni (1951) Genetics, 36, pp. 13-30Pavan, C., Dobzhansky, Th., da Cunha, A.B., Heterosis and elimination of weak homozygotes in natural populations of three related species of Drosophila (1957) Proc. Natl. Acad. Sci. USA, 43 (2), pp. 226-234de Souza, H.M.L., da Cunha, A.B., dos Santos, E.P., Assortative mating in polymorphic laboratory populations of Drosophila willistoni (1966) Egypt J. Genet. Cytol., 1, pp. 225-280de Souza, H.M.L., da Cunha, A.B., dos Santos, E.P., Adaptive polymorphism developed in laboratory populations of Drosophila willistoni (1968) Am. Nat., 102, pp. 583-586de Souza, H.M.L., da Cunha, A.B., dos Santos, E.P., Adaptive polymorphism of behavior evolved in laboratory populations of Drosophila willistoni (1970) Am. Nat., 104, pp. 175-189de Toledo, J.S., de Magalhães, L.E., da Cunha, A.B., An effect of change of environment on the frequencies of the lethal chromosomes in Drosophila willistoni (1966) Am. Nat., 100, pp. 693-696Wallace, B., Allelism of second chromosome lethals in Drosophila melanogaster (1950) Proc. Natl. Acad. Sci. USA, 36, pp. 654-65