2,433 research outputs found

    Easy methods for fluorescent staining of Neurospora nuclei.

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    Easy methods for fluorescent staining of Neurospora nuclei

    Effect of light on perithecial production in homothallic Neurospora species

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    Effect of light on perithecial production in homothallic Neurospora specie

    Main features of Spore killer systems in Neurospora.

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    Main features of Spore killer systems in Neurospora

    Magnetic and Thermodynamic Properties of the Collective Paramagnet-Spin Liquid Pyrochlore Tb2Ti2O7

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    In a recent letter [Phys. Rev. Lett. {\bf 82}, 1012 (1999)] it was found that the Tb3+^{3+} magnetic moments in the Tb2_2Ti2_2O7_7 pyrochlore lattice of corner-sharing tetrahedra remain in a {\it collective paramagnetic} state down to 70mK. In this paper we present results from d.c. magnetic susceptibility, specific heat data, inelastic neutron scattering measurements, and crystal field calculations that strongly suggest that (1) the Tb3+^{3+} ions in Tb2_2Ti2_2O7_7 possess a moment of approximatively 5μB\mu_{\rm B}, and (2) the ground state gg-tensor is extremely anisotropic below a temperature of O(100)O(10^0)K, with Ising-like Tb3+^{3+} magnetic moments confined to point along a local cubic diagonal(e.g.towardsthemiddleofthetetrahedron).SuchaverylargeeasyaxisIsinglikeanisotropyalonga diagonal (e.g. towards the middle of the tetrahedron). Such a very large easy-axis Ising like anisotropy along a direction dramatically reduces the frustration otherwise present in a Heisenberg pyrochlore antiferromagnet. The results presented herein underpin the conceptual difficulty in understanding the microscopic mechanism(s) responsible for Tb2_2Ti2_2O7_7 failing to develop long-range order at a temperature of the order of the paramagnetic Curie-Weiss temperature θCW101\theta_{\rm CW} \approx -10^1K. We suggest that dipolar interactions and extra perturbative exchange coupling(s)beyond nearest-neighbors may be responsible for the lack of ordering of Tb2_2Ti2_2O7_7.Comment: 8 POSTSCRIPT figures included. Submitted to Physical Review B. Contact: [email protected]

    Coating of alumina on ceno-spheres of fly-ash

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    A study is reported that fly-ash behaves as an excellent raw-material for synthesising hollow alumina composite. Coating of alumina onto the surface of ceno spheres was accomplished by controlled precipitation around pH-10. Dopants like Ni/Co have also been successfully tried. The resultant co-precipitated composites were then characterized using DTA, XRD,Particle size analysis and specific-gravity measurements. Calcination of co- precipitated samples at 1500°C, for 1h and haracterisation of the calcined product also discussed. The results indicate that alumina can be successfully coated on ceno-spheres

    Unusual landings of Aluterus monoceros (Linnaeus, 1758) along Vizhinjam coast

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    On the13th of July 2009, unusual heavy landings of Aluterus monoceros (unicorn leather jacket) of the family Monacanthidae were observed along the coast, from Vizhinjam to Marianadu about 40 km north of Vizhinjam (Fig. 1). These fishes, locally known as “komban clathy” or “mara clathy” are rarely observed in large numbers in the landings at Vizhinjam which has become a subject of surprise to the fishermen. This has been the first incident of such a heavy landing of bigger sized unicorn leather jacket in this area

    First report of Spotted reef crab off Vizhinjam coast

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    Carpilius maculatus (Linnaeus, 1758), commonly known as ‘Seven-eleven crab’, ‘Spotted reef crab’, ‘Dark finger coral crab’, or ‘Large spotted crab’ is a member of the family Carpiliidae. One male specimen of the spotted reef crab C. maculatus measuring 130 mm in carapace width was caught by a bottom set gill net along with Portunus sanguinolentus from the rocky area in Vizhinjam coastal waters

    Static Critical Behavior of the Spin-Freezing Transition in the Geometrically Frustrated Pyrochlore Antiferromagnet Y2Mo2O7

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    Some frustrated pyrochlore antiferromagnets, such as Y2Mo2O7, show a spin-freezing transition and magnetic irreversibilities below a temperature Tf similar to what is observed nonlinear magnetization measurements on Y2Mo2O7 that provide strong evidence that there is an underlying thermodynamic phase transition at Tf, which is characterized by critical exponents \gamma \approx 2.8 and \beta \approx 0.8. These values are typical of those found in random spin glasses, despite the fact that the level of random disorder in Y2Mo2O7 is immeasurably small.Comment: Latex file, calls for 4 encapsulated postscript figures (included). Submitted to Phys. Rev. Letters

    Magneto-transport characteristics of La1.4Ca1.6Mn2O7 thin film deposited by spray pyrolysis

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    Polycrystalline thin films of double layer manganite La_1.4Ca_1.6Mn_2O_7 (DLCMO) have been deposited by nebulized spray pyrolysis on single crystal LaAlO_3 substrates. These single phase films having grain size in the range 70-100 nm exhibit ferromagnetic transition at T_C ~ 107K. The short range ferromagnetic ordering due to in plane spin coherence is evidenced to occur at a higher temperature around 225 K. Insulator/semiconductor to metal transition occurs at a lower temperature T_P ~ 55K. The transport mechanism above T_C is of Mott`s variable range hopping type. Below T_C the current-voltage characteristics show non-linear behaviour that becomes stronger with decreasing temperature. At low temperatures below T_CA ~ 30K a magnetically frustrated spin canted state is observed. The DLCMO films exhibit resonable low field magnetoresistance and at 77K the magnetoresistance ratio is ~ 5% at 0.6 kOe and \~ 13% at 3 kOe.Comment: 14 pages, 7 figure
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