Mapping of AlxGa1–xAs band edges by ballistic electron emission spectroscopy

We have employed ballistic electron emission microscopy (BEEM) to study the energy positions in the conduction band of AlxGa1 – xAs. Epilayers of undoped AlxGa1 – xAs were grown by molecular beam epitaxy on conductive GaAs substrates. The Al composition x took on values of 0, 0.11, 0.19, 0.25, 0.50, 0.80 and 1 so that the material was examined in both the direct and indirect band gap regime. The AlxGa1 – xAs layer thickness was varied from 100 to 500 Å to ensure probing of bulk energy levels. Different capping layers and surface treatments were explored to prevent surface oxidation and examine Fermi level pinning at the cap layer/AlxGa1 – xAs interface. All samples were metallized ex situ with a 100 Å Au layer so that the final BEEM structure is of the form Au/capping layer/AlxGa1 – xAs/bulk GaAs. Notably we have measured the Schottky barrier height for Au on AlxGa1 – xAs. We have also probed the higher lying band edges such as the X point at low Al concentrations and the L point at high Al concentrations. Variations of these critical energy positions with Al composition x were mapped out in detail and compared with findings from other studies. Local variations of these energy positions were also examined and found to be on the order of 30–50 meV. The results of this study suggest that BEEM can provide accurate positions for multiple energy levels in a single semiconductor structure

Chiral-Odd and Spin-Dependent Quark Fragmentation Functions and their Applications

We define a number of quark fragmentation functions for spin-0, -1/2 and -1 hadrons, and classify them according to their twist, spin and chirality. As an example of their applications, we use them to analyze semi-inclusive deep-inelastic scattering on a transversely polarized nucleon.Comment: 19 pages in Plain TeX, MIT CTP #221

Interference Fragmentation Functions and the Nucleon's Transversity

We introduce twist-two quark interference fragmentation functions in helicity density matrix formalism and study their physical implications. We show how the nucleon's transversity distribution can be probed through the final state interaction between two mesons ($\pi^+\pi^-$, $K\bar K$, or $\pi K$) produced in the current fragmentation region in deep inelastic scattering on a transversely polarized nucleon.Comment: Final version to be published in Phys. Rev. Let

Types of Chinese fruit grower cooperatives and their supply chain relationships

Developing cooperatives among fruit farmers in China have been increasing regarded as essential for the Chinese fruit industry to become more competitive in both domestic and international markets. Over the past decade, various cooperative groups in rural areas have been formed with the political and financial support of local governments. This paper examines three current models of fruit supply chains involving farmer cooperatives in China. A comparison of these chains on the basis of impacts on both farmers and product quality is made. The advantages and disadvantages of local government involvement are discussed

North-South supply chain alliances between developed and less developed countries: A feasible fresh produce strategy?

Cross hemisphere (north-south) producer alliances are one way of supplying seasonal fresh produce for an extended period. The persimmon (Diospyros kaki) is a fruit that is widely consumed in Asia. An alliance of Australian growers, the Australian Persimmon Export Company (APEC), has been developing an international supply chain for its branded persimmons for about 12 years. An APEC alliance with a northern hemisphere supplier would allow supply of its brands for a longer season. In Baoji, Shaanxi province, western China, small areas of the same varieties of persimmon as marketed by APEC are replacing traditional varieties. Baoji persimmon growers are quite poor and disadvantaged by their remoteness from wealthier consumers in coastal provinces. Yet, with assistance, their fruit could meet APEC quality standards. Since early 2003, APEC and the Baoji local government have been exploring how to train local Chinese persimmon farmers to use the APEC production and marketing system. APEC's chain partners in markets such as Singapore and Malaysia could then receive high quality persimmons in early October, when supply is scarce. Returns would be enough to both increase the income of Baoji persimmon growers and invest in further market development that would benefit APEC and Baoji as chain partners. Pilot scale results to date have indicated that this approach to supply chain building is feasible, however, the ability to fund commercial scale application of the concept by all partners may prove to be a short-term limitation

Colloquialisation and the evolution of Australian English A cross-varietal and cross-generic study of Australian, British, and American English from 1931 to 2006

This paper investigates whether colloquialisation - a stylistic shift by which written genres come to be more similar to spoken genres - has played a role in the endonormativisation of the grammar of Australian English, a variety which has long been noted for its penchant for colloquialism. The study tracks changes in grammatical colloquialism from the early 20th century against the historical backdrop of the progressive decline in Britishness in Australia and the pervasive effects of “Americanisation”. The data are derived from a suite of parallel Brown-family corpora representing British, American, and Australian English of the 1930s, 1960s, 1990s and 2006. Multivariate techniques are used to delimit 26 “colloquial” and “anti-colloquial” grammatical features from a set of 83 potentially relevant features, and to examine changes in their frequencies between 1931 and 2006, in the three varieties, and across the three major genres of fiction, learned writing and press reportage

Ancestral RNA: The RNA biology of the eukaryotic ancestor

Our knowledge of RNA biology within eukaryotes has exploded over the last five years. Within new research we see that some features that were once thought to be part of multicellular life have now been identified in several protist lineages. Hence, it is timely to ask which features of eukaryote RNA biology are ancestral to all eukaryotes. We focus on RNA-based regulation and epigenetic mechanisms that use small regulatory ncRNAs and long ncRNAs, to highlight some of the many questions surrounding eukaryotic ncRNA evolution

Final state interactions and gauge invariant parton distributions

Parton distributions contain factorizable final state interaction effects originating from the fast-moving struck quark interacting with the target spectators in deeply inelastic scattering. We show that these interactions give rise to gauge invariance of the transverse momentum-dependent parton distributions. As compared to previous analyses, our study demonstrates the existence of extra scaling contributions from transverse components of the gauge potential at the light-cone infinity. They form a transverse gauge link which is indispensable for restoration of the gauge invariance of parton distributions in the light-cone gauge where the gauge potential does not vanish asymptotically. Our finding helps to explain a number of features observed in a model calculation of structure functions in the light-cone gauge.Comment: 34 pages, LaTeX, 10 figure

Anyonic statistics with continuous variables

We describe a continuous-variable scheme for simulating the Kitaev lattice model and for detecting statistics of abelian anyons. The corresponding quantum optical implementation is solely based upon Gaussian resource states and Gaussian operations, hence allowing for a highly efficient creation, manipulation, and detection of anyons. This approach extends our understanding of the control and application of anyons and it leads to the possibility for experimental proof-of-principle demonstrations of anyonic statistics using continuous-variable systems.Comment: 5 pages, 2 figures, appear in Phys. Rev.