Hypertrees: a study in language specification

A hierarchy of data structures, called the hypertree hierarchy, is presented which has strings and trees as its smallest two elements. A generalized frontiering operation is presented. Grammars, automata and regular expressions are extended to this hierarchy. These are shown to be equivalent and the resulting languages are called regular. This leads to a hierarchy of regular languages on the hypertree hierarchy. These are projected onto the set of strings by the frontier operation resulting in a true hierarchy of string languages. This hierarchy is called the (IO) algebraic language hierarchy. It has regular languages, context free languages and macro languages as its first three levels. It is contained in the set of context sensitive languages but is not equal to it. Other characterizations are presented

Annotation of the Nuclear Receptors in an Estuarine Fish species, \u3ci\u3eFundulus heteroclitus\u3c/i\u3e

The nuclear receptors (NRs) are ligand-dependent transcription factors that respond to various internal as well as external cues such as nutrients, pheromones, and steroid hormones that play crucial roles in regulation and maintenance of homeostasis and orchestrating the physiological and stress responses of an organism. We annotated the Fundulus heteroclitus (mummichog; Atlantic killifish) nuclear receptors. Mummichog are a non-migratory, estuarine fish with a limited home range often used in environmental research as a field model for studying ecological and evolutionary responses to variable environmental conditions such as salinity, oxygen, temperature, pH, and toxic compounds because of their hardiness. F. heteroclitus have at least 74 NRs spanning all seven gene subfamilies. F. heteroclitus is unique in that no RXRα member was found within the genome. Interestingly, some of the NRs are highly conserved between species, while others show a higher degree of divergence such as PXR, SF1, and ARα. Fundulus like other fish species show expansion of the RAR (NR1B), Rev-erb (NR1D), ROR (NR1F), COUPTF (NR2F), ERR (NR3B), RXR (NR2B), and to a lesser extent the NGF (NR4A), and NR3C steroid receptors (GR/AR). Of particular interest is the co-expansion of opposing NRs, Reverb-ROR, and RAR/RXR-COUPTF

The political career of Robert Whitehead

Robert Whitehead represented Nelson County in the Virginia General Assembly from 1942 until his death in 1960. He was widely recognized as the leading opponent to the dominant Byrd Organization in the state legislature. In this capacity, he often acted as a one-man party in opposition to the organization\u27s financial, political, educational and public services policies. A gifted orator and financial expert, Whitehead was often mentioned as a potential candidate for governor although he was never able to commit himself to a state-wide race. This thesis examines the political career of Robert Whitehead and evaluates his role in Virginia politics, particularly from 1948-1960

The magnitude and directions of strains and stresses in edge loaded concrete slabs

The concrete industry in the United States represents one of the fastest growing segments of the national economy. Many reasons for this may be given, among which are, the durability of concrete structures, the local availability of a large portion of the materials used in concrete, and its wide range of adaptability to the designs of engineers and architects. One of the most recent changes in concrete usage is the change from reinforced concrete to prestressed concrete. The term prestressed as used herein refers to any type of reinforced concrete in which the reinforcing material has a stress prior to the application of loads on the structure. Prestressed concrete is not new. It has been used successfully in Europe for several years and recently in the United States, particularly in buildings and bridges, to some extent. Many of the prestressed concrete projects in the United States are of a more or less experimental nature, trying different methods of stressing in order to perfect better anchorage and improve construction procedures. Recently the use of prestressed concrete has been proposed as a surface for highways. Concrete as a surface for highways has many advantages over other forms of paving, the main one being its relatively long usable life. This feature by itself makes concrete a widely used paving material. The disadvantages of concrete are many among which are, high initial cost, longer period of construction, and many construction joints which cause rough riding characteristics. Another disadvantage is a maintenance problem occurring when older concrete pavements fail due to transverse cracks. These cracks often occur during the first year or two of the pavement\u27s life, but do not cause serious problems until they become quite large and cause rough areas in the surface of the pavement. Transverse cracks are of two types. First, construction joints to allow for length changes caused by the expansion or contraction due to temperature changes in the pavement, and second, failures caused by deflection of the slab and subgrade due to heavy loads applied to the pavement. Cracks occurring in pavements poured on certain types of subgrade soil often develop a condition called pumping. This action consists of the deflection of the slab under moving loads which results in the ejection of water carrying soil particles in suspension. Conventional steel reinforcement has been used with varying degrees of success to correct the above mentioned disadvantages of concrete pavements. Cracks still occurred and construction joints were left at varying intervals. These cracks cause trouble on a somewhat reduced scale but the cost of a reinforced pavement is much higher in both material costs and labor costs. Prestressing concrete pavements may be a means of eliminating most of the cracks and many of the construction joints which are the major source of difficulty. This research project has as a goal a prestressed highway pavement which will have as many as possible of concrete\u27s inherent good advantages, and the fewest possible disadvantages --Introduction, pages 1-2