Computerised irrigation scheduling using spreadsheet models

Microcomputers are increasingly being used to help in the management of smallholder irrigation schemes in Third World countries. In many cases, commercially available spreadsheet packages offer advantages over established scientific programming languages. The paper starts with a review of computer models which have been developed for irrigation scheduling. Two criteria are identified which must be considered when developing computer models for this purpose: realistic data requirements and programs which are easy to understand. Spreadsheet packages provide a good introduction to computing and macro programming techniques can be used to customise spreadsheet models to create refined yet simple management tools. Two practical examples are presented from current research projects:

-a small scale scheme in Zimbabwe, where a spreadsheet model is used to produce irrigation schedules for smallholder farmers;

-a 20,000 ha project in Thailand, where a spreadsheet model makes use of feedback to improve main system scheduling.

     

The evaluation of ecological resources in the countryside for conservation purposes

County planning authorities in the British Isles are currently preparing plans (Structure Plans) which will determine the future pattern of land-use and one input to these is the evaluation of the relative ecological quality of different areas. These evaluations are being made on the basis of various criteria, such as extent, naturalness, richness and diversity, although there is no general agreement amongst ecologists or planners as to how such information should be combined to produce a single index. One possible index is suggested and the results obtained in a trial application are described.     

Sialomucin Complex (Muc4) Expression in Porcine Endometrium During the Oestrous Cycle and Early Pregnancy

The non‐invasive type of implantation in the pig is characterized by the maintenance of a thick glycocalyx coating on the uterine epithelial surface microvilli. Present study investigated the alteration in the sialomucin complex (Muc4) expression during the oestrous cycle and early pregnancy in the pig. Endometrial tissue samples were immunostained with the primary antibody to the Muc4 transmembrane subunit ASGP‐2. Muc4 immunostaining increased in the surface and glandular epithelia between days 5 and 10 of oestrous cycle. Immunostaining continued to increase on day 12 with the greatest intensity of uterine Muc4 immunostaining detected on day 15 of the oestrous cycle and early pregnancy. Endometrial Muc4 expression in cyclic gilts decreased dramatically during early proestrous but continued to remain abundant in the surface and glandular epithelium of pregnant gilts during the period of conceptus attachment to the uterine surface.     

Osmium Recycling in Subduction Zones

Peridotite xenoliths from the Cascade arc in the United States and in the Japan arc have neodymium and osmium isotopic compositions that are consistent with addition of 5 to 15 percent of subducted material to the present-day depleted mantle. These observations suggest that osmium can be partitioned into oxidized and chlorine-rich slab-derived fluids or melts. These results place new constraints on the behavior of osmium (and possibly other platinum group elements) during subduction of oceanic crust by showing that osmium can be transported into the mantle wedge.