A Quantitative Approach to Investigating the Hypothesis of Prokaryotic Intron Loss

Using a novel method, we show that ordered triplets of motifs usually associated with spliceosomal intron recognition are underrepresented in the protein coding sequence of complete Thermotogae, archaeal and bacterial genomes. The underrepresentation observed does not extend to the noncoding strand, suggesting that the cause of the asymmetry is related to mRNA rather than DNA. Our data do not suggest that the underrepresentation is due to gene transfer from eukaryotes. We speculate that one possible explanation for these observations is that the protein coding sequence of Thermotogae, Archaea and Bacteria was at some time in the past subjected to selection against certain motifs appearing in an order which might initiate splicing in environments harboring a functional spliceosome. This is consistent with, but certainly does not prove, a hypothetical scenario in which at least some prokaryote lineages once possessed a functional spliceosome. Thus, we present a new quantitative method, observations obtained using the method, and a speculative discussion of a possible explanation of the observations

R&D, Agency Costs and Capital Structure: International Evidence

We examine the impact of R&D intensity and agency costs on the value of firms across 13 economies. We find that R&D adds value while high agency costs reduce value. R&D adds value, however, even when agency costs are high. We show that in those firms where agency costs are high and R&D intensity is high the debt control hypothesis is at work. In contrast to the stylised fact of high R&D firms having low levels of debt, these firms have higher levels of debR&D, Agency Costs, Capital Structure

A Primary Ecological Survey of Dardanelle Reservoir Prior to Nuclear Facility Effluent Discharge

A preliminary ecological survey of Dardanelle Reservoir during the construction phase of Arkansas Power and Light Company\u27s nuclear generating facility was conducted from January 1970 through June 1974. The reservoir is characterized by relatively shallow depths and a high flow-thru rate. A number of features were associated with these characteristics. The reservoir carried a great deal of suspended material and exhibited high turbidities throughout most of the year. Typical thermal stratification and oxygen depletion were only rarely observed. Many of the physico-chemical parameters exhibited relatively high values in comparison to other Arkansas lakes and reservoirs, but due to absence of prolonged periods of stratification and stagnation, they did not undergo the extreme fluctuations sometimes observed in other reservoirs. Plankton and benthic samples were collected at least nine times per year from ten stations. These stations were selected to include both shallow and deep locations and to include points both within and outside the projected area of thermal influence when the plant became operational. There were a great variety of forms in the phytoplankton with the diatoms making up a considerable portion. The level of turbidity appeared to dampen somewhat the extreme fluctuations sometimes found in bloom periods. In the zooplankton the rotifers Brachionus, Keratella, and Polyarthra predominated followed by the microcrustaceans Cyclops and Bosmina. Both the plankton and the benthic fauna showed great seasonal variation. The benthic fauna consisted primarily of Chironomidae, Oligochaeta, and Hexagenia with the Chironomidae predominating in the shallower depths and the Oligochaeta exhibiting increased abundance and importance in the deeper stations

Do rational numbers play a role in selection for stochasticity?

When a given tissue must, to be able to perform its various functions, consist of different cell types, each fairly evenly distributed and with specific probabilities, then there are at least two quite different developmental mechanisms which might achieve the desired result. Let us begin with the case of two cell types, and first imagine that the proportion of numbers of cells of these types should be 1:3. Clearly, a regular structure composed of repeating units of four cells, three of which are of the dominant type, will easily satisfy the requirements, and a deterministic mechanism may lend itself to the task. What if, however, the proportion should be 10:33? The same simple, deterministic approach would now require a structure of repeating units of 43 cells, and this certainly seems to require a far more complex and potentially prohibitive deterministic developmental program. Stochastic development, replacing regular units with random distributions of given densities, might not be evolutionarily competitive in comparison with the deterministic program when the proportions should be 1:3, but it has the property that, whatever developmental mechanism underlies it, its complexity does not need to depend very much upon target cell densities at all. We are immediately led to speculate that proportions which correspond to fractions with large denominators (such as the 33 of 10/33) may be more easily achieved by stochastic developmental programs than by deterministic ones, and this is the core of our thesis: that stochastic development may tend to occur more often in cases involving rational numbers with large denominators. To be imprecise: That simple rationality and determinism belong together, as do irrationality and randomness

Creating an entrepreneurial frame of mind.

This dissertation is comprised of three essays that address the question: what specific cognitions lead to the formation of entrepreneurial intentions? Essay 1, Explaining and Predicting Entrepreneurial Intentions, investigates currently theorized antecedents of entrepreneurial intentions to determine the degree to which they predict entrepreneurial intentions. Findings suggest that proximal cognitions such as feelings, desires, emotions, and attitudes predict intention formation, albeit limited to situations where entrepreneurial behavior is imminent. Additionally, distal cognitions, such as biases, heuristics, scripts and maps, although useful in explaining intentions, are of little predictive value except when predicting the distal intention to become an entrepreneur in those with no entrepreneurial experience. Overall, results indicate that the antecedents used to explain entrepreneurial intentions are of limited predictive value. Essay 2, The Role of Cognitions in the Formation of an Entrepreneurial Mindset, examines which specific core-level antecedents act to form entrepreneurial mindset and how these cognitions relate to the formation of entrepreneurial intentions. It posits that core-level cognitions related to the self (entity-schema, possible-self, and self-efficacy) lead to the formation of an entrepreneurial mindset. The essay further posits that entrepreneurial mindset is the principal antecedent to entrepreneurial intentions. This conceptual investigation culminates in the presentation of a general theory of volitional behavior. Essay 3, An Empirical Evaluation of Entrepreneurial Mindset Using the Theory of Volitional Behavior, tests to what degree entrepreneurial mindset affects the formation of entrepreneurial intentions. Results indicate that individuals who possess an entrepreneurial entity-schema, an entrepreneurial possible-self, and entrepreneurial self-efficacy, on average, tend to form an entrepreneurial mindset. Furthermore, those individuals possessing an entrepreneurial mindset are more likely to form entrepreneurial intentions and ergo, are most likely to undertake entrepreneurial behavior. When taken together, these three essays show that (1) currently theorized antecedents of entrepreneurial intentions, although useful for explaining entrepreneurial intentions, are of limited use in the prediction of intention formation. (2) Core-level cognitions, specifically those relating to the self, represent a viable means of predicting formation of an entrepreneurial mindset. (3) Entrepreneurial mindset leads to the formation of entrepreneurial intentions, which offer one possible answer to the primary research question, what specific cognitions lead to the formation of entrepreneurial intentions