This is an introductory exposition to background material useful to appreciate various formulations of the Mordell–Lang conjecture (now established by recent spectacular work due to Vojta, Faltings, Hrushovski, Buium, Voloch, and others). It gives an exposition of some of the elementary and standard constructions of algebro-geometric models (rather than model-theoretic ones) with applications (...

i Summary/Zusammenfassung ii Summary Evaluation of dual purpose cowpea varieties for dry season feeding of ruminant animals Cowpea is of major importance to the livelihoods of millions of people in the tropics. Resource-poor smallholder farmers derive food, animal feed, cash and manure from the crop. Dual purpose cowpea has the potential to function as a key integrating factor in intensifying s...

The Eastern Himalayan region of Northeast (NE) India is home to a large number of indigenous rice varieties, which may serve as a valuable genetic resource for future crop improvement to meet the ever-increasing demand for food production. However, these varieties are rapidly being lost due to changes in land-use and agricultural practices, which favor agronomically improved varieties. A detail...

Lignin is an essential structural component of all land plants. It fills spaces in the cell wall between cellulose, hemicellulose, and pectin. Lignin provides the strength to plants from giant Sequoia trees to alfalfa growing in hay fields. A good analogy is that lignin is like the steel reinforcing rods in concrete. Life on earth would not be possible without lignin to allow plants to grow upr...

Large-scale yield trials have traditionally been used to rate the reactions of released sugarcane varieties to ratoon stunting disease (RSD). These trials are time-consuming and require large tracts of land and are therefore not suitable for incorporation into a routine programme of disease screening of new genotypes. Using a tissue blot-enzyme immunoassay (TBIA) to determine the percentage of ...

Biological diversity in areas of land use (called ‘agrodiversity’ in the People, Land Management and Environmental Change – PLEC project) is not simply a function of the diversity of species and varieties of biota. Naturally, it does concern standard ecological biodiversity aspects (often termed ‘agro-biodiversity’ or ‘agricultural biodiversity’). Usually it is used to tell the tale of how mode...

This paper studies the role of land as a factor of production in a simple monopolistic competition model of trade and geography. Overall we find that land for production is a powerful dispersion force. More specifically, we show that, in contrast to the new trade literature, a larger country will have lower wages, in general. Moreover, allowing for labor mobility, we show that agglomeration is ...

We study, as hypersurfaces in toric varieties, elliptic Calabi–Yau fourfolds for F-theory compactifications dual to E8 × E8 heterotic strings compactified to four dimensions on elliptic Calabi–Yau threefolds with some choice of vector bundle. We describe how to read off the vector bundle data for the heterotic compactification from the toric data of the fourfold. This map allows us to construct...

Mirror Symmetry for Calabi-Yau hypersurfaces in toric varieties is by now well established. However, previous approaches to it did not uncover the underlying reason for mirror varieties to be mirror. We are able to calculate explicitly vertex algebras that correspond to holomorphic parts of A and B models of Calabi-Yau hypersurfaces and complete intersections in toric varieties. We establish th...