Competing orders in a magnetic field: spin and charge order in the cuprate superconductors

We describe two-dimensional quantum spin fluctuations in a superconducting Abrikosov flux lattice induced by a magnetic field applied to a doped Mott insulator. Complete numerical solutions of a self-consistent large N theory provide detailed information on the phase diagram and on the spatial structure of the dynamic spin spectrum. Our results apply to phases with and without long-range spin density wave order and to the magnetic quantum critical point separating these phases. We discuss the relationship of our results to a number of recent neutron scattering measurements on the cuprate superconductors in the presence of an applied field. We compute the pinning of static charge order by the vortex cores in the `spin gap' phase where the spin order remains dynamically fluctuating, and argue that these results apply to recent scanning tunnelling microscopy (STM) measurements. We show that with a single typical set of values for the coupling constants, our model describes the field dependence of the elastic neutron scattering intensities, the absence of satellite Bragg peaks associated with the vortex lattice in existing neutron scattering observations, and the spatial extent of charge order in STM observations. We mention implications of our theory for NMR experiments. We also present a theoretical discussion of more exotic states that can be built out of the spin and charge order parameters, including spin nematics and phases with `exciton fractionalization'.Comment: 36 pages, 33 figures; for a popular introduction, see http://onsager.physics.yale.edu/superflow.html; (v2) Added reference to new work of Chen and Ting; (v3) reorganized presentation for improved clarity, and added new appendix on microscopic origin; (v4) final published version with minor change

Social competitiveness associated with rapid fluctuations in sperm quality in male fowl

When females copulate with multiple males, paternity is determined by the competitive ability of a male to access females and by the ability of its ejaculates to out-compete those of other males over fertilization. The relationship between the social competitiveness of a male and the fertilizing quality of its sperm has therefore crucial implications for the evolution of male reproductive strategies in response to sexual selection. Here, we present a longitudinal experimental study of the relationship between social status and sperm quality. We monitored sperm quality in socially naive male domestic fowl, Gallus gallus domesticus, before and after exposure to a social challenge which comprised two stages. In the first stage, social dominance was established in male pairs divergent in sperm quality, and in the second, social status was experimentally manipulated by re-shuffling males across pairs. We show that sperm quality fluctuates within males both before and after a social challenge. Importantly, such fluctuations followed consistently different patterns in males that displayed different levels of social competitiveness in the social challenge. In particular, following the social challenge, sperm quality dropped in males that won both contests while the sperm quality of males that lost both contests remained constant. Together, these results indicate that males of different social competitiveness are predisposed to specific patterns of fluctuations in sperm quality. These rapid within-male fluctuations may help explain the recent findings of trade-offs between male social and gametic competitive abilities and may help maintain phenotypic variability in these traits

Comparação de diluentes, diluições e tempo de armazenamento do sêmen sobre fertilidade, eclodibilidade e nascimento de pintos em matrizes pesadas Comparation of diluents, dilutions and storage time of heavy broiler breeder semen on fertility, hatchability and chick production

O objetivo deste trabalho foi identificar o melhor diluente, a diluição e o tempo de armazenamento para sêmen de galo. Um total de 60 galos e 630 galinhas com 55 semanas de idade foi artificialmente inseminado, uma vez por semana, por seis semanas consecutivas, utilizando-se 0,05 mL de sêmen/galinha. Os tratamentos foram: T1 = sêmen diluído com diluente comercial-DC; T2 = sêmen diluído com diluente Beltsville Poultry Sêmen Extender-BPSE; T3 = sêmen diluído com solução de Lake-LAKE; e T4 = sêmen fresco puro (Testemunha). Os níveis de diluição (D) foram D=0 (não-diluído), D=2 (1 parte de sêmen: 2 partes de diluente) e D = 4 (1 parte de sêmen: 4 partes de diluente). O tempo de repouso (H) do sêmen foi H = 0, sem repouso, H = 1, IA 1 hora após a coleta e H=24, IA 24 horas após a coleta (conservado em refrigerador entre 2 e 5°C). Os ovos foram avaliados por ovoscopia e ao nascer com quebra de ovos não-eclodidos. O sêmen puro, não-diluído e sem repouso, produziu os melhores resultados para fertilidade e nascimento, 87,2 e 79,5%, respectivamente. As médias de fertilidade e nascimento de pintos para sêmen diluído na proporção 1:2, com 2 horas de repouso, foram 84,8 e 76,3; 81,7 e 73,6; e 76,0 e 65,9%, respectivamente, para os diluentes LAKE, DC e BPSE. Quando se usou sêmen diluído, a diluição 1:2 produziu melhor resultado que 1:4. O período de repouso do sêmen, após a diluição, deve ser o menor possível. O diluente de Lake apresentou os melhores resultados entre os diluientes, equiparando-se ao uso de sêmen puro não-diluído e inseminado logo após a coleta.<br>The objective of this work was to identify the best semen extender, the dilution rate and the storage time for rooster semen. A total of 60 roosters and 630 hens with 55 weeks of age were artificially inseminated, once a week, by six consecutive weeks, using .05 mL of semen/hen. The treatments were: T1=semen diluted with commercial extender-DC; T2 =semen diluted with Beltsville Poultry Semen Extender-BPSE; T3=semen diluted with Lake solution-LAKE and T4=pure fresh semen (Control). The dilution levels (D) were D=0 (undiluted), D=2 (1 part of semen: 2 parts of extender) and D=4 (1 part of semen: 4 parts of extender). Storage time (H) was H=0, no rest, H=1, IA 1 hour after collection and H=24, IA 24 hours after collection (preserved in refrigerator between 2 and 5°C). The eggs were evaluated tby candling and at birth including the egg breaking for the no hatchable eggs. The fresh undiluted semen without storage produced the best averages for fertility (87.2) and birth (79.5%). The averages fertility and birth of the chicks for the semen diluted in the proportion of 1:2 with 24 hours of storage time were 84.8 and 76.3; 81.7 and 73.6 and 76.0 and 65.9, respectively for the extenders LAKE, DC and BPSE. When diluted semen was used, the dilution 1:2 produced better results than 1:4. The rest time for the semen, after dilution should be the minimum as possible. The Lake solution presented the best results among the extenders being equivalent to the use of fresh undiluted semen and inseminated just after the collection

Intraspecific variation in testis asymmetry in birds: evidence for naturally occurring compensation

In many taxa, the left and right testes often differ in size. The compensation hypothesis states that one testis of the pair serves as a ‘back-up’ for any reduced function in the other and provides a mechanism to explain intraspecific variation in degree and direction of gonad asymmetry. Although testis asymmetry is common in birds, evidence for natural testis compensation is unknown. Using a novel quantitative approach that can be applied to any bilateral organ or structure, we show that testis compensation occurs naturally in birds and can be complete when one testis fails to develop. Owing to a recurrent risk of testis impairment and an evolutionary trade-off between natural and sexual selections acting on the arrangement of internal organs in species with abdominal and/or seasonal testes, compensation adds an important, but neglected, dimension to measures of male reproductive investment

Morphological study of the testes of the dove Columba livia (Gmelin) (Columbidae, Columbiformes)

Known as "domestic dove", the Columba livia (Gmelin, 1789) is a columbidae species widely distributed in Brazil, whose reproductive biology has been studied by many researchers. The testes of 12 Columba livia males were collected and prepared for histologic examination under an optical microscope, the results of which were analysed and photographed. The tunica albuginea that covers the testes consists of a thick, not very cellular layer of dense connective tissue. Groups of interstitial cells with typical morphological appearance and surrounded by loose, well vascularized connective tissue are observable within the organ, between the seminiferous tubules. The seminiferous tubules are thick, intensely wound and, when seen in cross section, show Sertoli cells and spermatogenic lineage cells in different stages of development. These include spermatogonia (type A, clear; type A, dark; and type B), spermatocytes I and II, spermatids, and a large number of spermatozoons. Similarities are found between the histological findings described and those reported for the testes of Columbina talpacoti (Temminck, 1811)