Price synchronicity:the closing call auction and the London Stock Market

In this paper, we consider the impact of the introduction of a closing call auction on market quality of the London Stock Exchange. We employ the market model, RDD and MEC metrics of market quality. These signify substantial improvements to market quality at both the close and open for migrating stocks.We note that these improvements are larger at the open than the close. An important contribution of our paper is that we show that changes to market quality are stronger in those securities that have the lowest liquidity in the pre-call period. In contrast, market quality changes following the introduction of a closing call auction are approximately neutral for high-liquidity securities. We conclude that the implementation of a closing call auction, for high-liquidity securities may not enhance market quality.

The blurring boundaries between synchronicity and asynchronicity:new communicative situations in work-related Instant Messaging

Instant messaging is one of the most popular communication technologies in virtual teams, enabling interactions to intertwine whole working days, thus creating the sense of copresence for team members who are geographically dispersed. Through close linguistic analyses of naturally occurring data from a virtual team, this article discusses the implications of two novel communicative situations enabled by instant messaging: presence information and the persistence of transcript. The preliminary findings of this study indicate that these new communicative situations require the flouting or rethinking of previously existing interactional norms and that communicative practices employed by the team members are not yet conventionalized/normalized, the expectations and interpretations of interactional rituals and timing vary highly, even within the same virtual team.

Bacterial associations with salmonid eggs

Rainbow trout eggs Salmo gairdneri, Richardson, were incubated under a range of different environmental conditions. Recovery of bacteria from egg surfaces revealed that increased water temperature, slow water flow rates and high egg density all significantly increased egg surface bacterial populations. Live eggs were mainly colonized by Cytophaga sp., pseudomonas fluorescens and Aeromonas hydrophila. In contrast, dead eggs supported considerable numbers of fluorescent Pseudomonas sp. Analysis of potential nutrient sources for bacteria colonizing live egg surfaces revealed that small amounts of amino acids, phosphate and potassium may be lost by incubating eggs. Subsequently these nutrients were shown to be capable of supporting limited bacterial growth and reproduction. Dead eggs `leaked' increased amounts of the above nutrients which in turn supported higher bacterial numbers. In addition, biochemical analysis of eggs revealed amino acids and fatty acids that might be utilized by bacteria colonizing dead egg surfaces. Assessment of adhesion properties of bacteria frequently recovered from egg surfaces revealed high cell surface hydrophobicity as an important factor in successful egg colonization. Analysis of egg mortalities from groups of rainbow trout and brown trout (S.trutta L.) eggs maintained under two different incubation systems revealed that potentially a close correlation existed between egg surface bacterial numbers and mortalities in the egg during incubation. Innoculation of newly-fertilized eggs with bacteria demonstrated that groups of eggs supporting high numbers of P.fluorescens suffered significantly higher mortalities during the early part of their incubation. Exposure of incubating eggs to oxolinic acid, chlortetracycline and chloramphenicol demonstrated that numbers of bacteria on egg surfaces could be significantly reduced. However, as no corresponding increase in egg hatching success was revealed, the treatment of incubating eggs with antibiotics or antimicrobial compounds can not be recommended. In commercial hatcheries bacteria are only likely to be responsible for egg deaths during incubation when environmental conditions are unfavourable. High water temperatures, slow water flow rates and high egg density all lead to increased bacterial number of egg surfaces, reduced water circulation and low levels of dissolved oxygen. Under such circumstances sufficient amounts of dissolved oxygen may not be available to support developing embryos.

The histogenesis of lymphoid organs in Tilapia mossambica and antibody responses in adults and fry

The thymic anlagen appears in Tilapia mossambica at 2 days post hatching and becomes lymphoid at 5 days. Lymphoid cells were first seen in the pronephros at 14 days and in the spleen at approximately five weeks of age. Differentiation into red and white pulp regions was seen by 10 weeks of age. Light and electron microscopic studies of adult lymphoid organ revealed increases in size and lymphoid cell numbers. Adult thymus develops a clearer corticomedullary differentiation of thymic corpuscles in the medulla and in the splenic red and white pulp became more distinct. Melanomacrophage centres were seen in spleen and pronephros. Adult fish gave primary and secondary antibody responses following challenge with sheep red bloods cells (SRBC), Escherichia coli (E. coli) and human gamma globulin (HGG). Plaque forming cell and immunocytoadherence assays revealed that head kidney and spleen were major sites for antibody production and development of antigen reactive cells. Proliferative activity in these organs was revealed using autoradiography and scintillation counting. Increased levels of pyroninophilia were also seen following antigenic challenge. Pilot studies on adults revealed that they were capable of rejecting first and second set allografts and leucocytes from spleen and head kidney proliferated in mixed leucocyte cultures. Antibody responses to SRBC, E. coli and HGG develop at about 10-12 weeks of age. Fry given either a single injection of SRBC at 10 weeks or two injections of the same antigen at 10 weeks and 12 days later, failed to respond to a further challenge with SRBC 56 days after the first injection (A time when animals would normally respond positively to this antigen). Injection of E. coli at the same times resulted in a prolonged antibody response.

Hypoxia induces dilated cardiomyopathy in the chick embryo:mechanism, intervention, and long-term consequences

Background - Intrauterine growth restriction is associated with an increased future risk for developing cardiovascular diseases. Hypoxia in utero is a common clinical cause of fetal growth restriction. We have previously shown that chronic hypoxia alters cardiovascular development in chick embryos. The aim of this study was to further characterize cardiac disease in hypoxic chick embryos. Methods - Chick embryos were exposed to hypoxia and cardiac structure was examined by histological methods one day prior to hatching (E20) and at adulthood. Cardiac function was assessed in vivo by echocardiography and ex vivo by contractility measurements in isolated heart muscle bundles and isolated cardiomyocytes. Chick embryos were exposed to vascular endothelial growth factor (VEGF) and its scavenger soluble VEGF receptor-1 (sFlt-1) to investigate the potential role of this hypoxia-regulated cytokine. Principal Findings - Growth restricted hypoxic chick embryos showed cardiomyopathy as evidenced by left ventricular (LV) dilatation, reduced ventricular wall mass and increased apoptosis. Hypoxic hearts displayed pump dysfunction with decreased LV ejection fractions, accompanied by signs of diastolic dysfunction. Cardiomyopathy caused by hypoxia persisted into adulthood. Hypoxic embryonic hearts showed increases in VEGF expression. Systemic administration of rhVEGF165 to normoxic chick embryos resulted in LV dilatation and a dose-dependent loss of LV wall mass. Lowering VEGF levels in hypoxic embryonic chick hearts by systemic administration of sFlt-1 yielded an almost complete normalization of the phenotype. Conclusions/Significance - Our data show that hypoxia causes a decreased cardiac performance and cardiomyopathy in chick embryos, involving a significant VEGF-mediated component. This cardiomyopathy persists into adulthood.

Capabilities and roles of enterprise wikis in organizational communication

How can technical communicators in organizations benefit from wiki technology? This article alerts technical communicators to the possibilities of wiki-based collaborative content creation. It analyzes 32 articles on the use of corporate wikis, and compares them to three media choice theories: media richness theory, theory of media synchronicity, and common ground theory.