4,270 research outputs found

    Cooking the books around initial public offerings

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    Most prior studies suggest that firms opportunistically increase their earnings around an initial public offering (IPO). With a sample of 512 IPOs in 24 countries worldwide I find that IPO firms that are under suspicion of such behaviour, represent only a small proportion (+/-10%) of the total sample. My findings challenge the opportunistic perspective on earnings management and suggest that the information perspective is more pronounced. Furthermore, I find no evidence for a positive relationship between low investor protection regulations and opportunistic earnings management. It seems that stronger enforcement of investor protection laws do not counter self-interested behaviour

    OPTIMIZATION OF THE OPTICAL AND ELECTROCHEMICAL PROPERTIES OF DONOR-ACCEPTOR COPOLYMERS THROUGH FUNCTIONAL GROUP AND SIDE CHAIN MODIFICATION

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    Donor-acceptor copolymers have received a great deal of attention for application as organic semiconductors, in particular as the active layers in low-cost consumer electronics. The functional groups grafted to the polymer backbones generally dictate the molecular orbital energies of the final materials as well as aid in self-assembly. Additionally, the side chains attached to these functional groups not only dictate the solubility of the final materials, but also their morphological characteristics. The bulk of the research presented in this dissertation focuses on the synthesis and structure-property relationships of polymers containing novel acceptor motifs. Chapter 2 focuses on the synthesis of 1,2-disubstituted cyanoarene monomers as the acceptor motif for copolymerization with known donors. It was found that cyanation of both benzene and thiophene aromatic cores resulted in a decrease of the molecular orbital energy levels. Additionally, the small size of this functional group allowed favorable self-assembly and close π-stacking to occur relative to related acceptor cores carrying alkyl side chains as evidenced by UV-Vis and WAXD data. Chapter 3 describes the systematic variation of side chain branching length and position within a series of phthalimide-based polymers. Branching of the side chains on bithiophene donor units resulted in the expected increase in solubility for these materials. Furthermore, a correlation was found between the branching position, size, and the HOMO energy levels for the polymers. Additionally, it was demonstrated that branching the alkyl side chains in close proximity to polymer backbones does not disrupt conjugation in these systems. A novel acceptor motif based on the 1,3-indanedione unit is presented in Chapter 4. Despite the stronger electron withdrawing capability of this functional group relativeto phthalimide, it was found that polymers based on this unit have the same HOMO molecular orbital energy levels as those presented in Chapter 3. It was found, however, the presence of orthogonal side chains greatly enhanced the solubility of the final polymers. Additionally, UV-Vis and WAXD measurements revealed that thermal annealing had a profound effect on the ordering of these polymers. Despite the presence of orthogonal side chains, long range order and close π-stacking distances were still achieved with these materials. Finally, alkynyl “spacers” were used in Chapter 5 to separate the solubilizing alkyl side chains from the polymer backbones on bithiophene donor monomers. The alkynyl groups allowed for conjugated polymer backbones to be achieved as well as low HOMO energy levels. A correlation between the side chain size, π-stacking distances and HOMO-LUMO energy levels was measured in this polymer series

    Word-level Symbolic Trajectory Evaluation

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    Symbolic trajectory evaluation (STE) is a model checking technique that has been successfully used to verify industrial designs. Existing implementations of STE, however, reason at the level of bits, allowing signals to take values in {0, 1, X}. This limits the amount of abstraction that can be achieved, and presents inherent limitations to scaling. The main contribution of this paper is to show how much more abstract lattices can be derived automatically from RTL descriptions, and how a model checker for the general theory of STE instantiated with such abstract lattices can be implemented in practice. This gives us the first practical word-level STE engine, called STEWord. Experiments on a set of designs similar to those used in industry show that STEWord scales better than word-level BMC and also bit-level STE.Comment: 19 pages, 3 figures, 2 tables, full version of paper in International Conference on Computer-Aided Verification (CAV) 201

    Future direction of Sundstrand Electric Power

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    This case study focuses on whether Sundstrand should take the next evolutionary step in the aircraft electrical power market. This step is incorporation of Electrical Load Management Centers (ELMC\u27s) into its existing product lines. This paper will focus on four possible alternatives. The first alternative is to not expand in this direction. Whenever a venture is considered the potential benefits must out-weigh the potential risks or cost of entry. The second and third alternatives are very similar. Purchase a corporation that produces ELMC systems or a corporation that has technology similar to ELMC systems. These options are less favorable if Sundstrand already has technology and experience similar to ELMC\u27s or if internal development would be a more cost effective solution. The last option is to internally develop, market, and sell ELMC systems. A study of Sundstrand\u27s technical and financial resources will be necessary to determine if this is a feasible option

    Alien Registration- Valley, Effie J. (Fort Fairfield, Aroostook County)

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    https://digitalmaine.com/alien_docs/35705/thumbnail.jp

    Models of sex ratio evolution

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    Journal ArticleOur understanding of sex ratio evolution depends strongly on models that identify: (1) constraints on the production of male and female offspring, and (2) fitness consequences entailed by the production of different attainable brood sex ratios. Verbal and mathematical arguments by, among others, Darwin, Dusing, Fisher, and Shaw and Mohler established the fundamental principle that members of the minority sex tend to have higher fitness than members of the majority sex. They also outlined how various ecological, demographic and genetic variables might affect the details of sex-allocation strategies by modifying both the constraints and the fitness functions. Modern sex-allocation research is devoted largely to the exploration of such effects, which connect sex ratios to many other aspects of the biologies of many species

    Sexual dimorphism in the Hymenoptera

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    Journal ArticleSpectacular sex differences of many kinds occur abundantly among the wasps, bees and ants that make up the insect order Hymenoptera. In some cases these differences are so extreme that males and females of the same species have been classified in different genera for decades, until a chance observation of mating, or emergence from a single nest, establishes their identity. Even where the sexes are similar in morphology they lead very different lives. The hard-working females hunt for prey or other larval provisions, and in many taxa they carry these provisions back to a nest that they have constructed to protect their offspring. The males, by contrast, lead short lives (sometimes nasty and brutish), devoted to the single purpose of inseminating females. Countless variations on this theme have evolved during the long and successful history of the order, and other features of hymenopteran biology have allowed these sex differences of ecology to be translated into equally striking sex differences of behavior, morphology and physiology

    A review of human factors principles for the design and implementation of medication safety alerts in clinical information systems.

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    The objective of this review is to describe the implementation of human factors principles for the design of alerts in clinical information systems. First, we conduct a review of alarm systems to identify human factors principles that are employed in the design and implementation of alerts. Second, we review the medical informatics literature to provide examples of the implementation of human factors principles in current clinical information systems using alerts to provide medication decision support. Last, we suggest actionable recommendations for delivering effective clinical decision support using alerts. A review of studies from the medical informatics literature suggests that many basic human factors principles are not followed, possibly contributing to the lack of acceptance of alerts in clinical information systems. We evaluate the limitations of current alerting philosophies and provide recommendations for improving acceptance of alerts by incorporating human factors principles in their design

    Formal hardware verification of digital circuits

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    The use of formal methods to verify the correctness of digital circuits is less constrained by the growing complexity of digital circuits than conventional methods based on exhaustive simulation. This paper briefly outlines three main approaches to formal hardware verification: symbolic simulation, state machine analysis, and theorem-proving

    Sensitive Detection and Early Prognostic Significance of p24 Antigen in Heat-Denatured Plasma of Human Immunodeficiency Virus Type 1-Infected Infants

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    Immune complex formation causes underdetection of p24 antigen in human immunodeficiencyvirus(HIV)infection.Brieflyboilingdilutedplasma releasesallcomplexedantigen, which can then be measured by some commercial assays. In a retrospective pediatric cohort study, the specificity of this procedure in 390 uninfected samples was 96.9% after initial testing and 100% after neutralization. Sensitivity among 125 postnatal infected samples was, at a detection of 2 pg/ml., 96.0% (97% neutralizable) compared with 47.7% for regular antigen (76% neutralizable), 96% for polymerase chain reaction, and 77% for viral culture. The high sensitivity and specificity of heat-denatured antigen was confirmed by prospectively testing 113 additional samples.Quantitativeanalysisofsamplesfrominfectedinfants showedlowlevelsofp24 antigen in 29% of cord blood sera, a postnatal increase to levels that were during the first 6 months of life inversely associated with survival, and persistence of antigenemia thereafter independent of clinical status. Prevalence and antigen levels were significantly lower in mothers. The persistent antigenemia in children indicates that their immune systems cannot restrict HIV expression as efficiently as those of adult
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