The effects of magnetic field on the d-density wave order in the cuprates

We consider the effects of a perpendicular magnetic field on the d-density wave order and conclude that if the pseudogap phase in the cuprates is due to this order, then it is highly insensitive to the magnetic field in the underdoped regime, while its sensitivity increases as the gap vanishes in the overdoped regime. This appears to be consistent with the available experiments and can be tested further in neutron scattering experiments. We also investigate the nature of the de Haas- van Alphen effect in the ordered state and discuss the possibility of observing it.Comment: 5 pages, 4 eps figures, RevTex4. Corrected a silly but important typo in the abstrac

Study of Microstructure of Chill Cast Aluminium Bronzes (Cu-Al-Fe-Mn)

Substantial information is available on the microstr-uctures of high tensile aluminium bronzes but most of the literature is pertaining to the alloys containing nickel. In the present paper authors have studies and presented the microstructures of various nickel-free aluminium bronze alloys containing iron and manganese. As an exhau-stive amount of work had been done at National Metall-urgical Laboratory to study the mechanical properties of such aluminium bronze alloys in the chill cast condition, the present microstructure study is also limited to the as cast alloys

Study of microstructure of chill cast aluminium bronzes (Cu-AI-Fe-Mn)

SUBSTANTIAL information is available on the microstru-ctures of high tensile aluminium -bronzes but most of the literature is pertaining to the alloys containing nickel. Exhaustive amount of work was carried out by Gupta et al. at the National Metallurgical Laboratory to study the mechanical properties of aluminium-bronze alloys in the chill-cast condition without nickel addition, the results of which have already been reported in an earlier paper. The present paper relates to the study of microstructures of these chill-cast aluminium-bronze alloys. A few microstructures of Cu-Al-Fe system have been given by Copper Development Association in their recent publication on aluminium-bronzes.

Tempering of Die-steels based on indigenous materials

This paper present studies on the effects of quenching temperature, tempering temperature and time on the hardness of three die steels of similar carbon contents but having increasing chromium percentages. While tempering in the range of 150°C to 400°C it was observed that hardness decreased as quenching temperature was raised. All the steels showed secondary hardening phenomenon in relation to the variables mentioned above. It was also observed that on tempering the steels above 450°C, after prior quenching from increasing temperatures, hardness gradually increased upto the quenching temperature of 1100°C, beyond which followed a decrease in hardness. This phenomenon was the decrease in hardness. This phenomenon was the same at all tempering temperatures upto 601°C, but the increase in hardness from low quenching temperatures to the maximum quenching temperature was less at 450°C than at the higher temperatures and attained a maximum at 600°C secondary hardening decreased with the increase of quenching temperatur

The effect of two ectomycorrhizal fungi, Paxillus involutus and Suillus tomentosus, and of Bacillus subtilis on Fusarium damping-off in jack pine seedlings

On a testé l'effet de deux espèces de champignons ectomycorhiziens, le Paxillus involutus et le Suillus tomentosus, et une lignée de la bactérie Bacillus subtilis sur le Fusarium moniliforme, agent pathogène de la fonte des semis du pin gris (Pinus banksiana). Le P. involutus et B. subtilis ont tous les deux inhibé la croissance in vitro du F moniliforme. Les filtrats de culture de P. involutus et de B. subtilis ont été toxiques pour le F moniliforme, mais la formation de chlamydospores par le F moniliforme a été observée. Une meilleure survie des plantules a été observée lorsqu'elles étaient co-inoculées avec le P. involutus et le B. subtilis plutôt qu'avec le F moniliforme seulement. Le S. tomentosus n'a pas inhibé la croissance in vitro du F. moniliforme ni accru la survie des plantules de pin gris en présence de F moniliforme. Ce dernier a réduit la formation d'ectomycorhizes sur le pin gris par le P. involutus et le S. tomentosus. Le nombre d’unités formatrices de colonies du F. monoliforme a été significativement réduit quand les plantules ont été inoculées avec le P. involotus ou le B. subtilis seul ou en combinaison. D’autre part, le S. tomentosus n’a pas réduit le nombre d’unités formatrices de colonies du F. monoliforme. La suppression de la croissance du F. monoliforme par le P. involutus et le B. subtilis a entraîné la production de composés antifongiques.Two species of ectomycorrhizal fungi, Paxillus involutus and Suillus tomentosus, and a bacterial strain of Bacillus subtilis, were tested against Fusarium moniliforme, the causal agent of damping-off in jack pine (Pinus banksiana) seedlings. Both P. involutus and B. subtilis inhibited in vitro growth of F moniliforme. The culture filtrates of P. involutus and B. subtilis were toxic to F moniliforme, but chlamydospore formation of F moniliforme was observed. Greater jack pine seedling survival was observed when co-inoculated with P. involutus and B. subtilis than with F moniliforme alone. S. tomentosus neither inhibited in vitro growth of F moniliforme nor increased survival of jack pine seedlings against F moniliforme. F moniliforme reduced ectomycorrhiza formation on jack pine seedlings by P. involutus and S. tomentosus. The number of colony forming units of F moniliforme was significantly reduced when seedlings were inoculated with P. involutus and B. subtilis alone or in combination. S. tomentosus, on the other hand, did not reduce the number of colony forming units of F moniliforme. The suppression of F moniliforme growth by P. involutus and B. subtilis involved production of antifungal compounds

Incipient order in the t-J model at high temperatures

We analyze the high-temperature behavior of the susceptibilities towards a number of possible ordered states in the t-J-V model using the high-temperature series expansion. From all diagrams with up to ten edges, reliable results are obtained down to temperatures of order J, or (with some optimism) to J/2. In the unphysical regime, t<J, large superconducting susceptibilities are found, which moreover increase with decreasing temperatures, but for t>J, these susceptibilities are small and decreasing with decreasing temperature; this suggests that the t-J model does not support high-temperature superconductivity. We also find modest evidence of a tendency toward nematic and d-density wave orders. ERRATUM: Due to an error in the calculation, the series for d-wave supeconducting and extended s-wave superconducting orders were incorrect. We recalculate the series and give the replacement figures. In agreement with our earlier findings, we still find no evidence of any strong enhancement of the superconducting susceptibility with decreasing temperature. However, because different Pade approximants diverge from each other at somewhat higher temperatures than we originally found, it is less clear what this implies concerning the presence or absence of high-temperature superconductivity in the t-J model.Comment: 4 pages, 5 eps figures included; ERRATUM 2 pages, 3 eps figures correcting the error in the series for superconducting susceptibilitie

Benthos - Polychaetes

Polychaetes are one of the major benthic group of animals just like molluscs and crustaceans. Globally 12,620 species of Polychaetes are supposed to be occurring and in India around, 1,093 species representing 8.66% of the total number of polychaete species are known. Polychaetes are very important in the marine and brackish water ecosystems extending from the abyssal depths to the inter-tidal regions. Its major role is through the biomass formation in the benthic as well as in the pelagic aquatic systems as sedentary and pelagic polychaetes and through the different larval forms released by them. It also forms the major food for crustaceans, molluscs as well as for fishes. Because of the special adaptive nature of this group, Polychaetes are distributed in almost all ecological conditions, both in the macro and micro environments having different ranges of salinities and dissolved oxygen. Certain species survive in the anaerobic conditions also

Correlation Lengths in Quantum Spin Ladders

Analytic expressions for the correlation length temperature dependences are given for antiferromagnetic spin-1/2 Heisenberg ladders using a finite-size non-linear sigma-model approach. These calculations rely on identifying three successive crossover regimes as a function of temperature. In each of these regimes, precise and controlled approximations are formulated. The analytical results are found to be in excellent agreement with Monte Carlo simulations for the Heisenberg Hamiltonian.Comment: 5 pages LaTeX using RevTeX, 3 encapsulated postscript figure

Reptiles

List of commonly observed reptiles in mangroves are give