Letter from E. D. Ball

Letter concerning late recommendations for E. D. Ball

Bulletin No. 155 - The Beet Leafhopper and the Curly-Leaf Disease That It Transmits

The beet leafhopper (Eutettix tenella Baker), is the most serious pest of the western sugar beet. It has through the disease it tranmits caused periodic losses to the western sugarbeet industry, amounting in the aggregate to many millions of dollars. Curly-leaf, the disease which this insect transmits, has in some of its worst outbreaks caused the abandonment of thousands of acres of beets in certain districts and a serious reduction in tonnage of the remainder, so that the total loss in a single area has several times passed the million-dollar mark. Besides these striking and widespread outbreaks which fortunately have not been numerous, it has continued from year to year to reduce tonnage in certain districts until at least seven factories have temporarily or permanently suspended operation on account of losses from this source

Notes on the Cercopidae with Descriptions of Some New Species

No additions have been made to the records of Iowa Cercopidae since the writer presented his papers on this group in 1895 and 1897; in fact, only one new species has been added to the United States list since that time. There have, however, been a number of rather surprising additions and extensions of distribution and some of them point to the probability of two more species being found in Iowa and the distribution of two others being extended beyond what appeared at that time to be their probable limits

Snakes Swallowing Their Young

Doctor Herrick in his review of the Infancy of Animals in a recent number of Science raises the question of the accuracy of observations on snakes swallowing their young. As the writer once had what was probably a particularly favorable opportunity to witness this phenomenon, it occurs to him that the following facts may be worth recording

Bulletin No. 138 - How to Control the Grasshoppers

There is no longer any reason why a farmer or a community of farmers should allow their crops and meadows to be destroyed by swarms of grasshoppers. Our knowledge of their habits has increased and better methods of destruction are known, so that at the present time the grasshopper takes its place in the list of crop pests that can be controlled by those who desire to do so. In the old days when countless numbers of the Rocky Mountain locusts (M. spretus) settled down on the crops of the few scattering settlers of the plains or Intermountain region, there was rarely any possibility of successfully coping with them. The grasshoppers were too numerous and the settlers too few. The breeding grounds were hundreds of miles away and almost unknown. Grasshoppers were at that time rightfully considered a public calamity against which no provision could be made

A Review of the Tettigonidaae of North American North of Mexico

The present paper has been planned to serve a double purpose. Its first object being to furnish a means of separating and determining the members of this family found in the United States and Canada, together with their varieties and the synonomy as far as it has been worked out. Secondly, to give sufficiently accurate and detailed descriptions in all cases, even where not necessary in the separation of our own forms, so that later workers in the group and those from other parts will be able to discriminate between our species and closely allied forms from other regions, or to recognize our forms when found in other countries

Phased array-fed antenna configuration study

The scope of this contract entails a configuration study for a phased array fed transmit antenna operating in the frequency band of 17.7 to 20.2 GHz. This initial contract provides a basis for understanding the design limitations and advantages of advanced phased array and cluster feeds (both utilizing intergral MMIC modules) illuminating folded reflector optics (both near field and focused types). Design parametric analyses are performed utilizing as constraints the objective secondary performance requirements of the Advanced Communications Technology Satellite (Table 1.0). The output of the study provides design information which serves as a data base for future active phased array fed antenna studies such as detailed designs required to support the development of a ground tested breadboard. In general, this study is significant because it provides the antenna community with an understanding of the basic principles which govern near field phased scanned feed effects on secondary reflector system performance. Although several articles have been written on analysis procedures and results for these systems, the authors of this report have observed phenomenon of near field antenna systems not previously documented. Because the physical justification for the exhibited performance is provided herein, the findings of this study add a new dimension to the available knowledge of the subject matter

Phased array-fed antenna configuration study: Technology assessment

Spacecraft array fed reflector antenna systems were assessed for particular application to a multiple fixed spot beam/multiple scanning spot beam system. Reflector optics systems are reviewed in addition to an investigation of the feasibility of the use of monolithic microwave integrated circuit power amplifiers and phase shifters in each element of the array feed

Current research in cavitating fluid films

A review of the current research of cavitation in fluid films is presented. Phenomena and experimental observations include gaseous cavitation, vapor cavitation, and gas entrainment. Cavitation in flooded, starved, and dynamically loaded journal bearings, as well as squeeze films are reviewed. Observations of cavitation damage in bearings and the possibility of cavitation between parallel plates with microasperities were discussed. The transcavity fluid transport process, meniscus motion and geometry or form of the film during rupture, and reformation were summarized. Performance effects were related to heat transfer models in the cavitated region and hysteresis influence on rotor dynamics coefficients. A number of cavitation algorithms was presented together with solution procedures using the finite difference and finite element methods. Although Newtonian fluids were assumed in most of the discussions, the effect of non-Newtonian fluids on cavitation was also discussed

A Review of the Cercopidae of North America North Of Mexico

The family cercopidae, though of world-wide distribution, has comparatively few representatives within our borders, and those few have been but imperfectly known, the literature on the subject being scattered and fragmentary, the generic references often incorrect, and the specific determinations, owing to the extreme variability in color of some species, and the striking similarity of color between others, rendered very questionable. Scarcely one of the more common forms but what has been referred to under at least four different genera and several have more than that number of specific names