We examine the effect of strong three-dimensional quantum confinement on the thermopower and electrical conductivity of PbSe nanocrystal superlattices. We show that for comparable carrier concentrations PbSe nanocrystal superlattices exhibit a substantial thermopower enhancement of several hundred microvolts per Kelvin relative to bulk PbSe. We also find that thermopower increases monotonically as the nanocrystal size decreases due to changes in carrier concentration. Lastly, we demonstrate that thermopower of PbSe nanocrystal solids can be tailored by charge-transfer doping.

Figure 1: We describe a system that can reconstruct the pose of the hand from a single image of the hand wearing a multi-colored glove. We demonstrate our system as a user-input device for desktop virtual reality applications. AbstractArticulated hand-tracking systems have been widely used in virtual reality but are rarely deployed in consumer applications due to their price and complexity. In this paper, we propose an easy-to-use and inexpensive system that facilitates 3-D articulated user-input using the hands. Our approach uses a single camera to track a hand wearing an ordinary cloth glove that is imprinted with a custom pattern. The pattern is designed to simplify the pose estimation problem, allowing us to employ a nearest-neighbor approach to track hands at interactive rates. We describe several proof-of-concept applications enabled by our system that we hope will provide a foundation for new interactions in modeling, animation control and augmented reality.

Solid-solid junctions with an interfacial self-assembled monolayer ͑SAM͒ are a class of interfaces with very low thermal conductance. Au-SAM-GaAs junctions were made using alkanedithiol SAMs and fabricated by nanotransfer printing. Measurements of thermal conductance using the 3 technique were very robust and no thermal conductance dependence on alkane chain length was observed. The thermal conductances using octanedithiol, nonanedithiol, and decanedithiol SAMs at room temperature are 27.6± 2.9, 28.2± 1.8, and 25.6± 2.4 MW m −2 K −1 , respectively.

Summary:Interpretation of functional metabolic brain images requires understanding of metabolic shifts in working brain. Because the disproportionately higher uptake of glucose compared with oxygen ("aerobic glycolysis") during sensory stimulation is not fully explained by changes in levels of lactate or glycogen, metabolic labeling by [6-14 C]glucose was used to evaluate utilization of glucose during brief brain activation. Increased labeling of tricarboxylic acid cycle-derived amino acids, mainly glutamate but also ␥-aminobutyric acid, reflects a rise in oxidative metabolism during aerobic glycolysis. The size of the glutamate, lactate, alanine, and aspartate pools changed during stimulation. Brain lactate was derived from blood-borne glucose and its specific activity was twice that of alanine, revealing pyruvate compartmentation. Glycogen labeling doubled during recovery compared with rest and activation; only 4% to 8% of the total 14 C was recovered in lactate plus glycogen. Restoration of glycogen levels was slow, and diversion of glucose from oxidative pathways to restore its level could cause a prolonged reduction of the global O 2 /glucose uptake ratio. The rise in the brain glucose-oxygen uptake ratio during activation does not simply reflect an upward shift of glycolysis under aerobic conditions; instead, it involves altered fluxes into various (oxidative and biosynthetic) pathways with different time courses.