Long-term changes in the equatorial Pacific trade winds [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Past work has shown that surface zonal equatorial wind stress, zonally integrated from one side of the Pacific to the other, is the key variable for estimating long-term El Niño behavior in the eastern Pacific. ... We used detrended COADS pressure in the eastern and western equatorial Pacific and post-1960 detrended Florida State University equatorial wind stress zonally averaged across the Pacific to verify this relationship.

EFFECT OF GRAIN-BOUNDARY MICROSTRUCTURE ON CAVITY NUCLEATION IN A NICKEL-BASED SUPERALLOY.

A study is presented of grain-boundary cavitation produced in Nimonic 80A by cold-deformation and stress-free annealing. The cavities were found to originate either from transverse cracking of carbide particles, or from decohesion of the particle-grain boundary interfaces. This decohesion could occur either during deformation, or during annealing. The cavities were invariably located at or close to the point of impingement of a matrix slip band on the grain boundary, but not all slip bands at a particular boundary were associated with cavitation. Quantitative evidence is presented showing that the mean number of dislocations associated with each slip band increases with macroscopic strain, but there is considerable variation between slip bands. This accounts for the differential ability of slip bands to result in cavity nucleation.

Development of non-weak link bulk YBCO grain boundaries for high magnetic field eegimeering applications

A non-weak link joining technique has been developed for YBCO pseudo-crystals fabricated by seeded peritectic solidification based on the formation of a liquid phase which segregates from the platelet boundaries at temperatures above = 920 °C. Electrical and magnetic measurements on these boundaries suggest that their irreversibility field can be as high as 7 T at 77 K in fully oxygenated pseudo-crystals joined along their crystallographic ab-planes which is comparable to the irreversibility behaviour of the adjacent YBCO grains. © 1999 IEEE.

Magnetic field and current distributins in melt-textured YBa 2Cu 3O 7-x with an artificial grain boundary

Using a magneto-optical (MO) technique, magnetic field distributions have been measured in a melt-textured YBa 2Cu 3O 7-x bulk superconductor, joined to form an artificial grain boundary (GB), in an external magnetic field perpendicular to the sample surface. The magnetic field at a weak section of the GB shows different values between the field increasing up to 150mT and decreasing down to 0T after zero-field-cooling. Namely, the magnetic field in increasing field is higher than that in decreasing field, even in the same external field. This result supports a model in which such differences in magnetic field at the weak-link GB give rise to the hysteresis behavior in the field dependence of transport critical current density in polycrystalline samples. The field distributions across a well-joined region of the GB behave similarly to the adjoining bulk material and this result indicates the possibility of creating useful artifacts provided that the strongly coupled sections can be reproduced on a larger scale.

Socio-economic implications of the fish export trade in Uganda

Implications of the fish export trade on the people and the fisheries resource of Lake Victoria, Uganda were examined. Eight fish processing factories and ninety fishers were analyzed in terms of socio-economic characteristics of fishers and the economic characteristics of fish factories. Results indicated that industrial fish processors in Uganda are presently the main link between the artisanal fisher-folk and the overseas export markets. Their entry into the market has stabilized and expanded the fisher-folk market and average earnings. Fishers attributed improvement in incomes and living standards (76%) to positive changes in the fish market (78%) in the last 5 years (1994-1999). Ugandan fisher-folk communities are not seriously affected by the Nile perch exports (73%) because they normally have easy access to cheap fish at prices much less than urban prices and; depend mainly on alternative fish species of less export value. The price of Nile perch influences positively the price of Tilapia

Comment on 'processing and microstructure of single grain uranium-doped Y-Ba-Cu-O superconductor'

We comment on the paper by N Hari Babu et al. (2002 Supercond. Sci. Technol. 15 104-10) and point out misinterpretations of the chemical composition of U-bearing deposits observed in Y123. The observed small deposits are those of new compounds which do not contain Cu, rather than refined Y211 plus U, as stated by the authors. We further note that extensive literature, not quoted, is in disagreement by nearly an order of magnitude concerning the values of Pt and U doping at which the optimum value of Jc is obtained. Other related information, presently in the literature, which may be helpful to those working with this high temperature superconducting chemical system, is presented.