Laser Cooling of 85Rb Atoms to the Recoil Temperature Limit

We demonstrate the laser cooling of 85Rb atoms in a two-dimensional optical lattice. We follow the two-step degenerate Raman sideband cooling scheme [Kerman et al., Phys. Rev. Lett. 84, 439 (2000)], where a fast cooling of atoms to an auxiliary state is followed by a slow cooling to a dark state. This method has the advantage of independent control of the heating rate and cooling rate from the optical pumping beam. We operate the lattice at a Lamb-Dicke parameter eta=0.45 and show the cooling of spin-polarized 85Rb atoms to the recoil temperature in both dimension within 2.4 ms with the aid of adiabatic cooling

Brand Awareness and Price Dispersion in Electronic Markets

Price dispersion, the variance in price for identical products across retailers, is a persistent feature of Internet- based markets, even those mediated by shopping agents (shopbots). In this paper, we propose a model for explaining this price dispersion based on limited consumer awareness of competing retailers and brand sensitivity, the willingness to pay a premium to buy from a leading retailer. We show that full awareness and the absence of brand sensitivity are necessary for markets to be characterized by Bertrand competition. When both of these are not simultaneously true (which is likely for most Internet markets), a number of other pricing strategies become optimal. Branded (high awareness) retailers tend to charge higher prices on average, but in some circumstances will randomize their prices such that they will be lower price than unbranded retailers on some products or some of the time. We also show that even if an unbranded retailer can invest to improve awareness, they have weak incentives to do so as this increases price competition. These observations are consistent with empirical research on pricing in Internet-based markets and may offer a more complete story of Internet price dispersion than some of the leading alternative explanations

Early “Neolithics” of China: Variation and Evolutionary Implications

The growth and significance of scientific research into the origins of agriculture in China calls for fresh examination at scales large enough to facilitate explanation of cultural evolutionary processes. The Paleolithic to Neolithic transition (PNT) is not yet well-understood because most archaeological research on early agriculture cites data from the more conspicuous and common early Neolithic sites. In this, the first of two papers, we synthesize a broad range of early Neolithic archaeological data, including diagnostic artifacts, settlement patterns, site structure, and biological remains, to consider agriculture as a system-level adaptive phenomenon. Although farming by this period was already well-established in much of North China and the middle Yangtze River basin, echoes of the foraging past can be found in the persistence of hunting-related artifacts in North China’s Loess Plateau and aquatic-based intensification and vegeculture in South China. Our analysis of the growing body of Chinese data and projections using Binford’s hunting and gathering database indicate that agriculture was differentially developed, adopted, or resisted by foragers according to measurable, predictable initial conditions of habitat that influenced diet breadth. In a subsequent paper (Journal of Anthropological Research 73(3), 2017, doi: 10.1086/692660), we will use these findings as a platform for a deeper consideration of the emerging archaeological record of the PNT, and to develop hypotheses for the last foraging and first farming adaptations in China

Intensified Foraging and the Roots of Farming in China

In an accompanying paper (Journal of Anthropological Research 73(2):149–80, 2017), the authors assess current archaeological and paleobiological evidence for the early Neolithic of China. Emerging trends in archaeological data indicate that early agriculture developed variably: hunting remained important on the Loess Plateau, and aquatic-based foraging and protodomestication augmented cereal agriculture in South China. In North China and the Yangtze Basin, semisedentism and seasonal foraging persisted alongside early Neolithic culture traits such as organized villages, large storage structures, ceramic vessels, and polished stone tool assemblages. In this paper, we seek to explain incipient agriculture as a predictable, system-level cultural response of prehistoric foragers through an evolutionary assessment of archaeological evidence for the preceding Paleolithic to Neolithic transition (PNT). We synthesize a broad range of diagnostic artifacts, settlement, site structure, and biological remains to develop a working hypothesis that agriculture was differentially developed or adopted according to “initial conditions” of habitat, resource structure, and cultural organization. The PNT of China is characterized by multiple, divergent evolutionary pathways: between the eastern and western parts of North China, and between and the Yangtze Valley and the Lingnan region farther south