Kaluza-Klein description of geometric phases in graphene

In this paper, we use the Kaluza-Klein approach to describe topological defects in a graphene layer. Using this approach, we propose a geometric model allowing to discuss the quantum flux in $K$-spin subspace. Within this model, the graphene layer with a topological defect is described by a four-dimensional metric, where the deformation produced by the topological defect is introduced via the three-dimensional part of metric tensor, while an Abelian gauge field is introduced via an extra dimension. We use this new geometric model to discuss the arising of topological quantum phases in a graphene layer with a topological defect.Comment: 16 pages, version accepted to Annals of Physic

Weed Control by Means of Chemicals

Weed control by means of chemicals has become an important factor in our struggle to eradicate weeds. There are few weed problems which chemicals cannot at least aid. However, in many cases, their use is limited by their cost. It has generally been held that chemicals are too expensive for large infestations of weeds. In northwest Iowa where there are thousands of acres of European bindweed (Convolvulus arvensis L.) chemicals of the present day cannot be recommended on account of the cost. To control this noxious weed it has been necessary to resort to cultivation and competitive cropping, processes which take several years, and have for their objective a reduction in the amount of food reserves in the subterranean parts, to the point where there is not sufficient food material to regenerate new shoots

Leafy Spurge, Euphorbia Esula L.

Leafy spurge (Euphorbia Esula L.) has become a serious menace to agriculture in northwest Iowa and in the adjoining states, Minnesota, North and South Dakota. It was collected at Mount Pleasant (Henry County) in 1899 and at Ames (Story County) in 1907. This weed seems to develop most vigorously in northwestern Iowa, where large patches occur on many farms. In order to determine the most effective means of exterminating this weed pest, it was necessary to learn more about its life history, growth, habits and structure in areas where it was well established. An attempt has been made in this publication to place leafy spurge in its correct place taxonomically and to discuss the flowering, fruiting habits, pollination, seed studies, seed dispersal, root system, leaf, stem and root structures

Soil Moisture Relationship of the European Bindweed (Convolvulus Arvensis L.)

The European bindweed (Convohrulus arucnsis L.) has an extensive root system. A large number of feeding roots are located in the upper two feet but the main tap root often extends to a depth of twenty feet. Soil samples taken at one and two foot depths in 1933, 1934 and 1935, at Hawarden, Iowa, from corn ground, heavily infested with bindweed, and free from bindweed, showed very little difference in soil moisture content. As the soil moisture content was often below the wilting coefficient, it was found that the bindweed developed readily while the corn grew very little. European bindweed is able to complete successfully with corn because of its deeply penetrating root system

Control and eradication of European Bindweed

The European bindweed (Convolvulus arvensis L.), known also as Creeping Jennie and field bindweed, probably is present in every county in Iowa, although it is more prevalent in the northwestern part of the state. It is not uncommon to find tracts of 100 acres or more. Where a small grain field is heavily infested, the grain becomes lodged so that it is extremely difficult to cut with a grain binder, and the bundles do not dry readily. At times throughout the years 1930-1941, bindweed caused a complete failure of corn (fig. 1), grain and garden crops on certain tracts. In the states where European bindweed is most troublesome today, the weed was not serious up to the beginning of the twentieth century. This bulletin reports information obtained during the past 10 years from the experimental work on eradication of European bindweed at Hawarden and Cherokee, Iowa. The recommendations submitted are particularly applicable to Iowa

The Use of Tetrachlorethane in the Eradication of the European Bindweed (Abstract)

Tetrachlorethane, made by the addition of chlorine to acetylene, has proved to be effective in killing the European bindweed. By making holes 18 inches deep and having the holes 18 inches apart and placing two ounces of tetrachlorethane in each hole, a complete eradication of the European bindweed may be made with one application

The effect of city smoke on vegetation

A study of the smoke problem in Des Moines establishes clearly that the smoke and gases emitted by its many power and heating plant chimneys have a harmful effect upon trees, shrubs and other vegetation. To a large extent, plants serve as good indicators of smoke contamination in a community. In the immediate neighborhood of the smoke emitting establishments in Des Moines, only a few of the most resistant plants grow, all others being eliminated, A little farther away, where the smoke and gases are not so dense, some additional plants are found and so as the distance increases the number of plants increases until an area is reached where the air is not much contaminated and vegetation is normal. Around each large manufacturing establishment the vegetation may be mapped in belts of varying width, in each of which certain forms of plant life may be found, depending on susceptibility of smoke injury. In much the same way the entire area of Des Moines may be mapped in belts according to the influence of smoke injury on vegetation