Bacteriorhodopsin optoelectronic synapses.

Synapses are critical components of an artificial neural network. Bacteriorhodopsin thin film can be used to construct compact, finely graded synapses for an optoelectronic neural network, based on its photochromic properties. Measurements show that these photochromic changes are blocked at low temperature. Thermal gating will allow synapses to be written on the film optically and then read without erasure by the same light and also will permit local implementation of an associative learning rule for updating synaptic weights.

Interaction of diet composition and a reduced nocturnal temperature regimen in weanling pigs.

A three-trial experiment using 3- to 4-wk-old newly weaned pigs was conducted to evaluate the possible interaction between a 16-h reduced nocturnal temperature regimen (RNT16) and a lowered nursery diet lysine regimen on weaned pig and subsequent growing-finishing performance. Nursery temperature treatments were 1) a control temperature (CT) regimen of 30 degrees C constant air temperature lowered 2 C degree/wk and 2) a regimen beginning 1 wk after weaning in which the temperature from 1600 to 0800 was lowered 6 C degree from CT. Within each temperature treatment, all pigs were offered a diet containing 1.20% lysine for the 1st wk after weaning followed by 1.20 or 1.10% lysine to 10.5 kg and 1.00 or .90% lysine to 20 kg. There was no interaction of temperature regimen and diet on overall nursery performance. The RNT16 pigs had improved (P = .1) ADG (.351 vs .342 kg/d) with no difference (P > .1) in ADFI (.693 vs .680 kg/d) or G:F (.508 vs .506) compared with CT. Pigs fed the lower lysine sequence had poorer (P < .0001) ADG (.333 vs .360 kg/d) and G:F (.487 vs .527) than controls. There was also no effect (P > .1) of RNT16 vs CT on subsequent performance to slaughter weight for ADG (.770 vs .755 kg/d) or G:F (.309 vs .311). There was also no effect (P > .1) of a lowered nursery lysine sequence compared to control on growing-finishing ADG (.768 vs .757 kg/d) or G:F (.312 vs .309).(ABSTRACT TRUNCATED AT 250 WORDS)

Two reduced nocturnal temperature regimens for early-weaned pigs.

Two experiments, each consisting of three trials and using 3- to 4-wk-old newly weaned pigs, were conducted to evaluate the effects of two reduced nocturnal temperature regimens on weaned pig and subsequent growing-finishing performance and nursery energy (propane and electricity) use. In Exp. 1, nursery treatments were 1) a control temperature (CT) regimen of 30 degrees C constant air temperature lowered 2C degrees/wk and 2) a regimen for pigs in pens with hovers (MRNT-H) in which the temperature from 1900 to 0700 beginning 1 wk after weaning was lowered 6 C degrees from the 0700 to 1900 temperature setting, which was 3C degrees lower than CT. The nursery temperature treatments in Exp. 2 were 1) CT and 2) a 10C degrees reduction in air temperature (MRNT10) from 1900 to 0700 from CT beginning 1 wk after weaning. In addition, within each temperature, diet sequences of 1.2% lysine for 3 wk followed by 1.0% lysine vs 1.15% lysine offered continuously were evaluated. In Exp. 1, there was no effect (P greater than .1) of temperature on feed intake but ADG decreased (P less than .001) in two of the three trials for MRNT-H vs CT and feed/gain worsened (P less than .05) in all trials. In Exp. 2, there was no difference between MRNT10 and CT for ADG and feed/gain. No interaction was observed between nursery diet and temperature regimen for weaned pig performance. There was no effect (P greater than .1) in either experiment of nursery temperature on subsequent growing-finishing performance. Overall energy savings comparing the MRNT-H and CT treatments were 68 MJ per weaned pig. Energy savings for Exp. 2 were 79 MJ per weaned pig. Application of cyclical temperatures in a controlled manner can result in energy savings of approximately $50 per pig weaned under the conditions of these experiments.

A modified reduced nocturnal temperature regimen for early-weaned pigs.

A four-trial experiment utilizing 3- to 4-wk-old newly weaned pigs was conducted to evaluate the effect of a modified reduced nocturnal (MRNT) nursery temperature regimen on weaned pig and subsequent grower-finisher performance. Nursery treatments were 1) a control temperature (CT) regimen of 30 degrees C constant air temperature lowered 2 degrees C/wk and 2) a regimen beginning 1 wk after weaning in which the temperature from 1900 to 0700 was lowered 6 degrees C from CT. Weaned pigs gained faster (P less than .01) in the MRNT treatment than in the CT treatment, with gains in Trials 1, 2, 3 and 4 being .39 vs .37, .28 vs .27, .38 vs .37 and .39 vs .36 kg/d, respectively. This improvement in gain was due to an increase (P less than .005) in feed intake for the same periods (.60 vs .58; .48 vs .42; .59 vs .58; .63 vs .58 kg/d). There was no difference in feed conversion (P greater than .1). There was no effect (P greater than .1) of MRNT vs CT on subsequent performance to slaughter weight for average daily gain (.69 vs .69 kg/d), average daily feed (2.22 vs 2.23 kg/d) or gain/feed (.31 vs .31). These results support the conclusions that weaned pigs eat more feed and gain faster with a reduced nocturnal temperature scheme and that there are no carry-over effects during the growing-finishing phase.

Membrane resistivity estimated for the Purkinje neuron by means of a passive computer model.

A multicompartment passive electrotonic computer model is constructed for the cerebellar Purkinje cell of the guinea-pig. The model has 1089 coupled compartments to accurately represent the morphology of the Purkinje cell. In order that the calculated behavior of the model fit the published electrophysiological observations of somatic and dendritic input conductance, the neural membrane resistivity must be spatially non-uniform. The passive electrical parameter values for which the model best fits the observations of input conductances, pulse attenuation and current-clamp voltage transients are rm,dend = 45,740 omega cm2, rm,soma = 760 omega cm2, ri = 225 omega cm and cm = 1.16 microF/cm2 (the membrane and cytoplasm specific resistivities and membrane specific capacitance, respectively). The model with these parameter values is electrically compact, with electrotonic length X = 0.33 and dendritic dominance ratio p = 0.44. Analysis of the calculated voltage transient of the multicompartment model by the methods of equivalent-cylinder cable theory is shown to result in very different and unreliable conclusions. The significance for neuronal function of the estimated electrical parameter values is discussed. The possible effect of active conductances on these conclusions is assessed.