Three-dimensional deformation measured in an alaskan glacier

Measurements of movement along 28 boreholes reveal the three-dimensional flow field in a 6 million cubic meter reach of Worthington Glacier, a temperate valley glacier located in Alaska. Sliding at the bed accounted for 60 to 70 percent of the glacier's surface motion. Strain rates in the ice were low from the surface to a depth of about 120 meters, but then increased rapidly toward the bed. Ice deformation was not affected by temporal changes in the sliding rate. The three-dimensional pattern of motion indicates that plane strain, which is often assumed by models, is a poor approximation of this viscous flow.     

Effect of temperature on inflorescence development and sex expression of mono- and poly-embryonic mango (Mangifera indica L.) cultivars

Summary

The effect of temperature on inflorescence development and sex expression in two mono-embryonic (`Irwin' and `Sensation'), and two poly-embryonic (`Nam Dok Mai' and `Kensington') mango cultivars was studied. Trees were subjected to natural winter temperatures to induce flowering prior to transfer into controlled environment glasshouse rooms under day/night temperature regimes of 15/5, 20/10, 25/15 and 30/208C for 20 weeks. Inflorescence development did not progress when trees were held at 15/58C. Cooler temperatures (20/108C) delayed the start of anthesis (42.4.d) compared with trees grown at 25/158C (23.d) and 30/208C (16.1.d). At 20/108C, the delay in the start of anthesis was greatest for `Sensation' (55.5.d) and least for `Nam Dok Mai' (25.5.d) while at other temperatures there was little difference between cultivars. The distribution of hermaphrodite flowers within the inflorescence was independent of temperature with the highest percentage found in the apical half of the inflorescence. There was an inverse relationship between the length of the anthesis period and temperature, with anthesis occurring over 30.d at 20/108C and reducing to fewer than 10.d at 30/208C. Temperature also had an inverse effect on the total number of flowers per inflorescence with 619.6.6.108.0 (mean for all cultivars) at 20/108C decreasing to 431.3.6.80.5 at 30/208C.     

Effects of plastic anti‐pecking devices on food intake and behaviour of laying hens fed on pellets or mash

1. This study investigated effects of plastic anti‐pecking devices on food intake and behaviour to assess their applicability in commercial layer flocks.

2. In experiment 1, 72 individually caged ISA Brown pullets were fitted at 16 weeks of age (point of lay) with either ‘ring’ or ‘bumper’ beak devices or no device (control), half being fed on pellets and half on mash. The devices were held in place by lugs inserted in the nares.

3. There was evidence of discomfort immediately after fitting the devices, but not thereafter. In the first week, the devices reduced food intake, and were removed from 7 (15%) birds that lost weight consistently. Between 16 and 21 weeks, however, there were no significant effects of beak treatment or food form on either total food intake or egg production with the 65 remaining birds.

4. Beak treatment did not affect feeding efficiency (food intake per minute of feeding). The only behaviour affected was pecking at birds in adjacent cages, which was reduced with the ring device.

5. At 21 weeks, the birds were placed together in groups of 4 to 6 in 12 pens, each group consisting of birds from one of the 6 original treatments, and their behaviour was observed in experiment 2 between 21 and 23 weeks.

6. The only effects of beak treatment on behaviour were that pecking at pen walls was increased with the ring device, while pulling and eating feathers from group mates was seen mainly with control birds fed on pellets. Two birds were cannibalised in a control group on pellets.

7. Devices came off 3 (7%) birds in experiment 1 and were replaced, and rings slipped over lower mandibles of 2 (5%) birds in experiment 2 and were corrected.

8. At 23 weeks, beak lengths were increased with ring and bumper treatments, and pecking damage scores were low with all treatments.

9. It is concluded that these devices are not applicable commercially, but further trials would be justified with new improved designs.