Why Rice Farmers Don't Sail: Coastal Subsistence Traditions and Maritime Trends in Early China

The Lower Yangtze River Valley is a key region for the early development of rice farming and the emergence of wet rice paddy field systems. Subsistence evidence from Neolithic sites in this area highlights the importance of freshwater wetlands for both plant and animal food resources. Early Neolithic rice cultivators looked inland, especially to wetlands and nearby woodlands, for their main protein sources. Links to the sea among these Neolithic populations are notably scarce. Due to the high yields of wet rice, compared with other staple crops as well as dryland rice, the wetland rice focused subsistence strategy of the Lower Yangtze would have supported high, and increasing, local population densities. Paddy agriculture demands labor input and water management on a large scale, which would have stimulated and reinforced trends towards more complex societies, such as that represented by Liangzhu in the lower Yangtze region. Population growth could have been largely absorbed locally, suggesting that population packing, not migration, was the dominant trend. Other case studies of agricultural dispersal, for the Korean Peninsula and Japan further illustrate the lack of correlation between the spread of rice agriculture and wet rice cultivation. Although wet rice cultivation was a pull factor that drew local populations towards increased density and increased social complexity, it did not apparently push groups to migrate outwards. Instead, the transition from wetland to rain fed rice cultivation systems and/or the integration of rice with rain fed millet crops are much more likely to have driven the demographic dynamics that underpin early farmer migrations and crop dispersal

MCH and thermoregulation

Homeothermy represents a remarkable step in animal evolution, albeit at a very high cost in terms of metabolic demand. The maintenance of core body temperature in mammals represents one of the prominent physiological components contributing to the basal metabolic rate. Homeostatic thermoregulation is coordinated by the central nervous system by means of different strategies, spanning from behavioral modifications, aimed at finding a better environment, to the activation or inhibition of key regulatory mechanisms, that are mainly driven by the autonomic nervous system. The hypothalamic neuropeptide MCH plays a pivotal role in regulating basal metabolism, and the activation of this system results in a slowing down of the metabolic rate, and also stimulates food intake. On the contrary, blocking the MCH system, in animal models, promotes a lean phenotype with higher body temperature. Even though MCH is not involved in thermoregulatory processes, modifying MCH activity induces metabolic rate modifications and thermoregulation is modified accordingly. The activation of the MCH system also leads to the dampening of the normal daily oscillation of body temperature. The well-known involvement of MCH in wake sleep cycle regulation, by stabilizing sleep, and in particular REM sleep, reinforces the hypothesis that the functions of metabolism, thermoregulation, and sleep regulation are closely linked

Enantioselective synthesis of proline derivatives by 1,3-dipolar cycloadditions

Research devoted to the synthesis of highly substituted prolines, which are hepatitis C virus inhibitors, using 1,3-dipolar cycloadditions (1,3-DC) of azomethine ylides is described. In the first part, a diastereoselective approach using an inexpensive lactate-derived acrylate as dipolarophile is described. In the second part, our efforts using simple and easily accessible chiral silver(I) and gold(I) complexes as catalysts for enantioselective synthesis of proline derivatives are reviewed. In this case, chiral phosphoramidites and binap have been used as privileged ligands. Parallel to these experimental results, considerable effort was dedicated to run semiempirical density functional theory (DFT) calculations to explain and justify the stereoselectivity of each process.This work has been supported by the DGES of the Spanish Ministerio de Ciencia e Innovación (MICINN) (Consolider INGENIO 2010 CSD2007-00006, FEDER-CTQ2007-62771/BQU, and by the Hispano-Brazilian project PHB2008-0037-PC), Generalitat Valenciana (PROMETEO/2009/039), and by the University of Alicante (GITE-09020-UA)