3,514 research outputs found

    Spawning periodicity of milkfish, Chanos chanos

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    Daily samplings were conducted in the waters of Batbatan Island from April 17 to June 11, 1977 in order to collect milkfish (Chanos chanos ) eggs. The numbers of eggs collected is tabulated by lunar period. Milkfish fry are more abundant during the new and full moon periods, and periodicity does exist, during the first and last quarter periods

    Breeding and larval rearing of the milkfish Chanos chanos (Pisces: Chanidae)

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    Contribution No. 11 of the Aquaculture Department, Southeast Asian Fisheries Development Center, P.O. Box 256, Iloilo City 5901, Philippines.Two sexually maturing female milkfish were captured in April 1977 and induced to spawn by means of acetone-dried Pacific salmon pituitary powder. The eggs were fertilized and incubated and the resultant young reared to 74-day old, 11 cm long fingerlings. Newly fertilized eggs averaged 1.16 mm in diameter and each had a narrow perivitelline space containing several cortical granules which disappeared within a few minutes. The yolk was slightly yellowish, devoid of oil globules and very finely granulated. Embryonic development was very similar to that of other pelagic fish eggs and hatching occurred between 35 to 36 hr at a salinity of 32 ppt and a temperature range of 28.4-29.2°C.This study was partially supported through a grant to the SEAFDEC Aquaculture Department by the International Development Research Centre of Canada, under Project No. 3-P-74-0146

    Bayesian co-estimation of selfing rate and locus-specific mutation rates for a partially selfing population

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    We present a Bayesian method for characterizing the mating system of populations reproducing through a mixture of self-fertilization and random outcrossing. Our method uses patterns of genetic variation across the genome as a basis for inference about pure hermaphroditism, androdioecy, and gynodioecy. We extend the standard coalescence model to accommodate these mating systems, accounting explicitly for multilocus identity disequilibrium, inbreeding depression, and variation in fertility among mating types. We incorporate the Ewens Sampling Formula (ESF) under the infinite-alleles model of mutation to obtain a novel expression for the likelihood of mating system parameters. Our Markov chain Monte Carlo (MCMC) algorithm assigns locus-specific mutation rates, drawn from a common mutation rate distribution that is itself estimated from the data using a Dirichlet Process Prior (DPP) model. Among the parameters jointly inferred are the population-wide rate of self-fertilization, locus-specific mutation rates, and the number of generations since the most recent outcrossing event for each sampled individual

    Electron effective mass in Sn-doped monoclinic single crystal β\beta-gallium oxide determined by mid-infrared optical Hall effect

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    The isotropic average conduction band minimum electron effective mass in Sn-doped monoclinic single crystal β\beta-Ga2_2O3_3 is experimentally determined by mid-infrared optical Hall effect to be (0.284±0.013)m0(0.284\pm0.013)m_{0} combining investigations on (010010) and (2ˉ01\bar{2}01) surface cuts. This result falls within the broad range of values predicted by theoretical calculations for undoped β\beta-Ga2_2O3_3. The result is also comparable to recent density functional calculations using the Gaussian-attenuation-Perdue-Burke-Ernzerhof hybrid density functional, which predict an average effective mass of 0.267m00.267m_{0} (arXiv:1704.06711 [cond-mat.mtrl-sci]). Within our uncertainty limits we detect no anisotropy for the electron effective mass, which is consistent with most previous theoretical calculations. We discuss upper limits for possible anisotropy of the electron effective mass parameter from our experimental uncertainty limits, and we compare our findings with recent theoretical results

    The Mre11-Rad50-Nbs1 complex mediates activation of TopBP1 by ATM

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    The activation of ATR-ATRIP in response to double-stranded DNA breaks (DSBs) depends upon ATM in human cells and Xenopus egg extracts. One important aspect of this dependency involves regulation of TopBP1 by ATM. In Xenopus egg extracts, ATM associates with TopBP1 and thereupon phosphorylates it on S1131. This phosphorylation enhances the capacity of TopBP1 to activate the ATR-ATRIP complex. We show that TopBP1 also interacts with the Mre11-Rad50-Nbs1 (MRN) complex in egg extracts in a checkpoint-regulated manner. This interaction involves the Nbs1 subunit of the complex. ATM can no longer interact with TopBP1 in Nbs1-depleted egg extracts, which suggests that the MRN complex helps to bridge ATM and TopBP1 together. The association between TopBP1 and Nbs1 involves the first pair of BRCT repeats in TopBP1. In addition, the two tandem BRCT repeats of Nbs1 are required for this binding. Functional studies with mutated forms of TopBP1 and Nbs1 suggested that the BRCT-dependent association of these proteins is critical for a normal checkpoint response to DSBs. These findings suggest that the MRN complex is a crucial mediator in the process whereby ATM promotes the TopBP1-dependent activation of ATR-ATRIP in response to DSBs

    Elastic properties of the Non-Fermi liquid metal CeRu4Sb12Ce Ru_4 Sb_{12} and the Dense Kondo semiconductor CeOs4Sb12Ce Os_4 Sb_{12}

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    We have investigated the elastic properties of the Ce-based filled skutterudite antimonides CeRu4_{4}Sb12_{12} and CeOs4_{4}Sb12_{12} by means of ultrasonic measurements. CeRu4_{4}Sb12_{12} shows a slight increase around 130 K in the temperature dependence of the elastic constants CC11_{11}, (CC11_{11}-CC12_{12})/2 and CC44_{44}. No apparent softening toward low temperature due to a quadrupolar response of the 4ff-electronic ground state of the Ce ion was observed at low temperatures. In contrast CeOs4_{4}Sb12_{12} shows a pronounced elastic softening toward low temperature in the longitudinal CC11_{11} as a function of temperature (TT) below about 15 K, while a slight elastic softening was observed in the transverse CC44_{44} below about 1.5 K. Furthermore, CeOs4_{4}Sb12_{12} shows a steep decrease around a phase transition temperature of 0.9 K in both CC11_{11} andC C44_{44}. The elastic softening observed in CC11_{11} below about 15 K cannot be explained reasonably only by the crystalline electric field effect. It is most likely to be responsible for the coupling between the elastic strain and the quasiparticle band with a small energy gap in the vicinity of Fermi level. The elastic properties and the 4ff ground state of Ce ions in CeRu4_{4}Sb12_{12} and CeOs4_{4}Sb12_{12} are discussed from the viewpoint of the crystalline electric field effect and the band structure in the vicinity of Fermi level.Comment: 9 pages, 11 figures, regular pape

    Phase diagram of YBa2_2Cu3_3O7−y_{7-y} at T<<Tc_c based on Cu(2) transverse nuclear relaxation

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    Two maxima in transverse relaxation rate of Cu(2) nuclei in YBa2_2Cu3_3O7−y_{7-y} are observed, at T = 35 K and T = 47 K. Comparison of the 63^{63}Cu(2) and 65^{65}Cu(2) rates at T = 47 K indicates the magnetic character of relaxation. The enhancement at T = 47 K of fluctuating local magnetic fields perpendicular to the CuO2_2 planes is connected with the critical fluctuations of orbital currents. Maximum at T = 35 K is connected with the appearance of inhomogeneous supeconducting phase. Together with data published to date, our experimental results allow to suggest a qualitatively new phase diagram of the superconducting phase.Comment: 4 LaTEX pages + 3 figures in *.ps forma

    Charge Transfer-Mediated Dramatic Enhancement of Raman Scattering upon Molecular Point Contact Formation

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    Charge-transfer enhancement of Raman scattering plays a crucial role in current-carrying molecular junctions. However, the microscopic mechanism of light scattering in such nonequilibrium systems is still imperfectly understood. Here, using low-temperature tip-enhanced Raman spectroscopy (TERS), we investigate how Raman scattering evolves as a function of the gap distance in the single C60-molecule junction consisting of an Ag tip and various metal surfaces. Precise gap-distance control allows the examination of two distinct transport regimes, namely tunneling regime and molecular point contact (MPC). Simultaneous measurement of TERS and the electric current in scanning tunneling microscopy shows that the MPC formation results in dramatic Raman enhancement that enables one to observe the vibrations undetectable in the tunneling regime. This enhancement is found to commonly occur not only for coinage but also transition metal substrates. We suggest that the characteristic enhancement upon the MPC formation is rationalized by charge-transfer excitation
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