Nature © Macmillan Publishers Ltd 1997the same direction. A zero value of H j indicates ferromagnetically coupled films. H j is known 7,14 to oscillate as a function of t because of the RKKY interaction. We can clearly distinguish two situations. In Fig. 4b (Cu spacer grown at room temperature) only a few oscillations take place, the oscillation with the short wavelength l being marginal. This is in contrast to the theoretical expectations 7 , which require l to dominate over Λ for geometrically perfect samples. On the other hand, when the Cu spacer is grown at low temperatures, more oscillations appear (Fig. 4c), and l dominates over Λ. We note that cooling a room-temperature-deposited wedge structure does not change the results given in Fig. 4b. Thus, lowtemperature deposition is essential to minimize thickness fluctuations. We also note that, in for example Fe/Cr multilayers, just the opposite occurs: the shortest-wavelength oscillation is favoured by high-temperature growth 15 .The smallest oscillations detected in this experiment correspond to an energy change of ϳ10 −8 eV per atom. This value represents a challenge both to first-principles calculations and to spectroscopies aimed at unveiling the electronic structure of solids. Moreover, although exceedingly small, this energy scale participates in deter-mining a macroscopic observable (in this case the threshold magnetic field H s ) and thus might play an important role in the design of metallic nanostructures for device application. Ⅺ

Extant African great apes and humans are thought to have diverged from each other in the Late Miocene. However, few hominoid fossils are known from Africa during this period. Here we describe a new genus of great ape (Nakalipithecus nakayamai gen. et sp. nov.) recently discovered from the early Late Miocene of Nakali, Kenya. The new genus resembles Ouranopithecus macedoniensis (9.6 -8.7 Ma, Greece) in size and some features but retains less specialized characters, such as less inflated cusps and better-developed cingula on cheek teeth, and it was recovered from a slightly older age (9.9 -9.8 Ma). Although the affinity of Ouranopithecus to the extant African apes and humans has often been inferred, the former is known only from southeastern Europe. The discovery of N. nakayamai in East Africa, therefore, provides new evidence on the origins of African great apes and humans. N. nakayamai could be close to the last common ancestor of the extant African apes and humans. In addition, the associated primate fauna from Nakali shows that hominoids and other noncercopithecoid catarrhines retained higher diversity into the early Late Miocene in East Africa than previously recognized.hominoid evolution

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