Children's use of looking behavior as a cue to detect another's goal

Three studies examined children's understanding of the role that looking behavior plays in revealing another's desired goal. In each study, participants were asked which of 2 objects a protagonist wanted to obtain. Four-year-olds did not infer that an object examined via prolonged looking was more likely to be the protagonist's goal than an object that was either glanced at or inadvertently touched. Instead, they were accurate only when the protagonist looked at one of two potential goals. In contrast, the majority of 6-year-olds (and adults in Experiment 1) consistently regarded prolonged looking as the more important cue of the protagonist's goal. These age differences suggest that development is characterized by an increasing appreciation that goal is revealed by comparative differences in the quality of perceptual connectedness to objects in the world. One explanation for these age differences is that preschoolers are limited in their understanding of the difference between perceiving with full attention and without it.     

Ca2+ differentially regulates conventional protein kinase Cs' membrane interaction and activation

The regulation of conventional protein kinase Cs by Ca2+ was examined by determining how this cation affects the enzyme's 1) membrane binding and catalytic function and 2) conformation. In the first part, we show that significantly lower concentrations of Ca2+ are required to effect half-maximal membrane binding than to half-maximally activate the enzyme. The disparity between binding and activation kinetics is most striking for protein kinase C betaII, where the concentration of Ca2+ promoting half-maximal membrane binding is approximately 40-fold higher than the apparent Km for Ca2+ for activation. In addition, the Ca2+ requirement for activation of protein kinase C betaII is an order of magnitude greater than that for the alternatively spliced protein kinase C betaI; these isozymes differ only in 50 amino acids at the carboxyl terminus, revealing that residues in the carboxyl terminus influence the enzyme's Ca2+ regulation. In the second part, we use proteases as conformational probes to show that Ca2+dependent membrane binding and Ca2+-dependent activation involve two distinct sets of structural changes in protein kinase C betaII. Three separate domains spanning the entire protein participate in these conformational changes, suggesting significant interdomain interactions. A highly localized hinge motion between the regulatory and catalytic halves of the protein accompanies membrane binding; release of the carboxyl terminus accompanies the low affinity membrane binding mediated by concentrations of Ca2+ too low to promote catalysis; and exposure of the amino-terminal pseudosubstrate and masking of the carboxyl terminus accompany catalysis. In summary, these data reveal that structural determinants unique to each isozyme of protein kinase C dictate the enzyme's Ca2+-dependent affinity for acidic membranes and show that, surprisingly, some of these determinants are in the carboxyl terminus of the enzyme, distal from the Ca2+-binding site in the amino-terminal regulatory domain.     

Six-Phase Voltage Source Inverter Driven Induction Motor

A six-phase six-step voltage-fed induction motor is presented. The inverter is a transistorized six-step voltage source inverter, while the motor is a modified standard three-phase squirrel-cage motor. The stator is rewound with two three-phase winding sets displaced from each other by 30 electrical degrees. A model for the system is developed to simulate the drive and predict its performance. The simulation results for steady-state conditions and experimental measurements show very good correlation. It is shown that this winding configuration results in the elimination of all air-gap flux time harmonics of the order (6v ±1, v = 1,3,5,...). Consequently, all rotor copper losses produced by these harmonics as well as all torque harmonics of the order (6v, v = 1,3,5,...) are eliminated. A comparison between-the measured instantaneous torque of both three-phase and six-phase six-step voltage-fed induction machines shows the advantage of the six-phase system over the three-phase system in eliminating the sixth harmonic dominant torque ripple.     

Fabrication of Long Lengths of Epitaxial Buffer Layers on Biaxially Textured Nickel Substrates Using a Continuous Reel-to-Reel Dip-Coating Unit

A low-cost, nonvacuum, solution precursor route has been developed to produce epitaxial oxide buffer layers of Eu₂O₃ or La₂Zr₂O₇ on biaxially textured Ni (100) tapes. A reel-to-reel continuous dip-coating unit consisting of a constant-tension tape transport system attached to a controlled atmosphere furnace was fabricated. Nickel tapes were pulled through a 2-methoxyethanol solution of europium methoxyethoxide/acetate or lanthanum zirconium methoxyethoxide. The double-sided dip-coated tapes were then annealed in a preheated furnace at 1000°–1100°C with a high flow rate of Ar/H₂ (4%) gas. The dip-coated buffers were dense, continuous, crack-free, and epitaxial with a single cube texture. A critical current ( J _c) of >1 MA/cm² at 77 K and self-field was obtained for YBa₂Cu₃O_7-δ (YBCO) films with a layer sequence of YBCO ( ex situ BaF₂ process)/CeO₂ (sputtered)/YSZ (sputtered)/Eu₂O₃ (dip-coated)/nickel. We have produced 1–2 m lengths of epitaxial buffer layers on textured nickel substrates using a nonvacuum process for the first time.