Reflection electron energy loss spectroscopy during initial stages of Ge growth on Si by molecular beam epitaxy

Using a conventional reflection high-energy electron diffraction gun together with an electron energy loss spectrometer, we have combined in situ measurements of inelastic scattering intensities from Si L2,3 and Ge L2,3 core losses with reflection electron diffraction data in order to analyze the initial stages of Ge heteroepitaxy on Si(001). Diffraction data indicate an initial layer-by-layer growth mode followed by island formation for Ge thicknesses greater than 0.8–1.1 nm. The electron energy core loss data are consistent with a simple model of grazing incidence electron scattering from the growing Ge film. Reflection electron energy loss spectroscopy is found to be highly surface sensitive, and the energy resolution and data rate are also sufficiently high to suggest that reflection electron energy loss spectroscopy may be a useful real-time, in situ surface chemical probe during growth by molecular beam epitaxy

Nonlithographic epitaxial Sn_xGe_(1–x) dense nanowire arrays grown on Ge(001)

We have grown 1-µm-thick Sn_xGe_(1–x)/Ge(001) epitaxial films with 0 < x < 0.085 by molecular-beam epitaxy. These films evolve during growth into a dense array of Sn_xGe_(1–x) nanowires oriented along [001], as confirmed by composition contrast observed in scanning transmission electron microscopy in planar view. The Sn-rich regions in these films dominate optical absorption at low energy; phase-separated Sn_xGe_(1–x) alloys have a lower-energy band gap than homogeneous alloys with the same average Sn composition

A new grass frog from Namibia

A new species of grass frog of lhe genus Ptychadena is described from northern Namibia. Although superficially similar to Ptychadena schillukorum and Ptychadena mossambica, the new species differs In advertisement call, and external characters. An examination of a series of published sonagrams indicates that Ptychadena floweri must be regarded as a junior synonym of P. schillukorum

Life Histories of Frogs in the Namib Desert

Four anuran taxa inhabit the central Namib: Xenopus laevis, Tomopterna delalandei cryptotis, Phrynomerus annectens and Bufo vertebrate hoeschi. Xenopus is confined to permanent pools in the Kuiseb river canyon. Tomopterna extends further into the Namib, but is restricted to the Kuiseb river bed. The Kuiseb is normally dry, receiving water only briefly (as floods) during the rainy season. These floods are responsible for moving adults and larvae. Phrynomerus and Bufo occur on granite inselbergs. The inselbergs provide shelter mainly in the form of cracks under granite exfoliations. Large runoff surfaces collect the low rainfall (25 mm per year) in depressions in which the frogs breed. Phrynomerus is only active at night; males are aggressive towards one another; oviposition takes place in deep pools and development takes at least eight weeks. Bufo is active during the heat of the day; oviposition takes place in warm shallow pools; development takes about three week

The distribution of Bufo poweri in southern Africa

Bufo poweri is shown to be distinguishable from B. garmani on the basis of different male advertisement calls. A survey of published and unpublished sonagrams, and data summarizing sonagrams of calls, was used to determine the geographic ranges of the two species. B. garmani is found in the north and east, and B. poweri in the south and west of Africa. Further fieldwork is required at the boundary between the two species

Face and Its Effect on Modern Historical Memory: Nanjing, China’s Massacre and Japan’s Incident

Rising tensions and an increased number of incidents between China and Japan in the current century show that the Nanjing Massacre has had an indisputable effect on modern Sino-Japanese relations politically and socially. Iris Chang’s book of popular history, The Rape of Nanking (1997), both renewed scholarly research and moved the debate into the public eye. This shift in the debate has led to continuing tensions between the two societies even as their governments officially maintain a peaceful relationship. The culture of “face” has made these Sino-Japanese tensions consistently intractable in the 21st century and sparked a number of anti-Japan protests in China. After Japan betrayed its position as inferior to the superior China by committing atrocities upon the Chinese people and has since refused to directly apologize for these atrocities, the Chinese people have been unable to resolve the issue of their humiliation as a countr

Description of a tetraploid Tomopterna (Anura: Ranidae) from South Africa

A new tetraploid species of sand frog, genus Tomopterna, is described from the eastern Cape. On the basis of mtDNA sequences, allozymes and advertisement calls, it appears to have arisen as a hybrid between the adjacent diploid populations of T. delalandii and T. cryptotis. The hybridization event is estimated to have occurred 1,5 MVA. Excluding Xenopus, this is the only allotetraploid member of an advanced frog family that is known

Comparison of toe pads of some southern African climbing frogs

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Local order measurement in SnGe alloys and monolayer Sn films on Si with reflection electron energy loss spectrometry

Measurements of local order are demonstrated in Sn-containing alloys and epitaxial monolayer thickness films by analysis of extended-edge energy loss fine structure (EXELFS) data obtained by reflection electron energy loss spectrometry (REELS). These measurements of short-range order provide a complement to the chemical information obtained with REELS and long-range order obtained using reflection high energy electron diffraction. The results suggest that EXELFS measurements are practical for samples mounted on the growth manipulator in a molecular beam epitaxy chamber. Advantages and limitations of reflection EXELFS are discussed

Description of a new moss frog from the south-western Cape (Anura: Ranidae: Arthroleptella)

A new species of moss frog, genus Arthroleptella, is described from the Kleinrivier mountains of the south-western Cape. It is morphologically indistinguishable from the other three species in the area. The four Cape species are allopatric, each has a unique male advertisement call, and preliminary molecular data shows consistent differences