Effect of several production factors on two varieties of rapeseed in the central United States

Two varieties of winter rapeseed (Brassica napus) (Cobra and Liborius) were planted at Brownstown, IL to evaluate the effect of planting date, nitrogen (N) rate, N application timing, and tillage on grain yield and oil content of the grain, grain moisture, plant lodging, winter survival, and plant N content. Results indicated that planting rapeseed approximately one to two weeks prior to winter wheat in this region is preferable to planting earlier. Grain yield showed a significant linear increase with delayed planting date from 25 August to 24 September. Grain yield also increased quadratically with increasing N rate (with an optimum of about 250 kg N/ha) and increased (0.15 Mg/ha) due to splitting the N fertilizer into two even applications. An increase in grain yield was accompanied by an increase in grain moisture with Liborius (late maturing) having significantly greater grain moisture than Cobra. Winter survival increased linearly with delayed planting date but, was accompanied by a significant quadratic increase in plant lodging. Chisel, as compared to disk tillage, increased plant lodging slightly, but decreased winter survival slightly. Neither delayed planting, N rate, nor splitting of spring N affected oil content. Liborius produced significantly more oil than did Cobra.     

Spatially resolved spin-injection probability for gallium arsenide

We report a large spin-polarized current injection from a ferromagnetic metal into a nonferromagnetic semiconductor, at a temperature of 100 Kelvin. The modification of the spin-injection process by a nanoscale step edge was observed. On flat gallium arsenide [GaAs(110)] terraces, the injection efficiency was 92%, whereas in a 10-nanometer-wide region around a [111]-oriented step the injection efficiency is reduced by a factor of 6. Alternatively, the spin-relaxation lifetime was reduced by a factor of 12. This reduction is associated with the metallic nature of the step edge. This study advances the realization of using both the charge and spin of the electron in future semiconductor devices.     

Pseudohermaphrodite rat: end organ insensitivity to testosterone

The pseudohermaphrodite rat is characterized by lack of androgen-dependent differentiation. Treatment of these rats with testosterone failed to produce the expected changes in preputial and adrenal gland weights and hexobarbital metabolism. This insitivity of the end organ to testosterone could not be explained by defective formation of dihydrotestosterone.     

Porosity aspects of the regeneration of soil structure after compaction

The natural regeneration of soil structure following compaction was studied on a stagnogleyic paleoargillic brown earth (Albaquic Paleudalf) at Rothamsted Experimental Station. The compaction treatment was produced by wheelings, and the area between the wheelings was used as the control.The wheeled and unwheeled areas were sampled 4 times, in spring and after harvest in 1979 and 1980 The following techniques were used to monitor regeneration: measuring the profile of the soil surface in the field and laboratory measurements of air-filled pore space, water retention, shrinkage and clod density, micromorphometry and mercury intrusion.Compaction decreased the macroporosity (pores >60 μm diameter) by over a half. Pores <6 μm diameter were unaffected by compaction. Natural regeneration of porosity in the top 5 cm was achieved within 18 months, but the soil below remained compacted for longer. The regenerated structure consisted mainly of planar voids induced by physical processes unlike the unwheeled soil which was characterised by packing voids and biopores.     

Spontaneous internal desynchronization of locomotor activity and body temperature rhythms from plasma melatonin rhythm in rats exposed to constant dim light

Background  

Daylight saving time is widely adopted. Little is known about its influence on the daily rest-activity cycles. We decided to explore the effects of transition into daylight saving time on the circadian rhythm of activity.     

Does agricultural intensification cause tipping points in ecosystem services?

Landscape Ecology - Agricultural intensification is being widely pursued as a policy option to improve food security and human development. Yet, there is a need to understand the impact of...