7,234 research outputs found

    Are Bond Covenants Priced?

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    In this paper we ask the empirical question are bond covenants priced? Consistent with the Costly Contracting Hypothesis (CCH) developed by Smith and Warner (1979), we find that they are. We document a negative relation between the promised yield on corporate debt issues and the presence of covenants. We also find that loans made to high-growth firms are more likely to include restrictive covenants than loans made to low-growth firms. We show that the inclusion of a covenant varies systematically with macroeconomic factors as well as with supply-side factors, especially the identity of the lending institution. Finally, we show that consistent with the CCH, firms that elect to issue private rather than public debt are smaller, have greater growth opportunities, less long term debt, fewer tangible assets, and include more covenants in their debt agreements. An important byproduct of our analysis is to demonstrate empirically that the decision to include a covenant and the corresponding promised yield are determined simultaneously. Consequently, statistical models that ignore this simultaneity in analyzing the effects of covenants, like single-equation probit models, are misspecified and generate unreliable statisticsAgency Costs, Costly Contracting, Debt Covenants

    Regulation of Arabidopsis 14-3-3 gene expression by GABA.

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    The function in plants of the non-protein amino acid, gamma-aminobutyric acid (GABA) is poorly understood. In this study, we show that GABA down-regulates the expression of a large sub-set of 14-3-3 gene family members in Arabidopsis thaliana seedlings in a calcium, ethylene and abscisic acid-dependent manner. Gene expression is not affected when seedlings are supplied with glutamate, a precursor of GABA. The repression of 14-3-3 gene expression by GABA is dependent on functional ethylene and abscisic acid signalling pathways, since the response is lost in the etr1-1, abi1-1 and abi2-1 mutants. Calcium measurements show that in contrast to glutamate, GABA does not elicit a cytoplasmic calcium elevation, suggesting that the GABA response is unlikely to be mediated by glutamate receptors, as has been suggested previously. We suggest that in addition to its role as a stress-related metabolite, GABA may regulate gene expression in Arabidopsis, including members of the 14-3-3 gene family

    Developmental genetics

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    Plant methods:putting the spotlight on technological innovation in the plant sciences.

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    Plant Methods is a new journal for plant biologists, specialising in the rapid publication of peer-reviewed articles with a focus on technological innovation in the plant sciences. The aim of Plant Methods is to stimulate the development and adoption of new and improved techniques and research tools in plant biology. We hope to promote more consistent standards in the plant sciences, and make readily accessible laboratory and computer-based research tools available to the whole community. This will be achieved by publishing Research articles, Methodology papers and Reviews using the BioMed Central Open Access publishing model. The journal is supported by a prestigious editorial board, whose members all recognise the importance of technological innovation as a driver for basic science

    The culture of enthesopathies: Differences in musculoskeletal stress markers between samples in a historic population

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    Identification of rice blast disease-suppressing bacterial strains from the rhizosphere of rice grown in Pakistan.

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    Sixteen bacterial strains isolated from the roots and rhizosphere of rice plants growing in saline and non-saline soils from the Shorkot area of Pakistan were tested for their ability to promote plant growth and reduce the incidence of rice blast disease. When applied to the soil, many of the isolated rhizobacterial strains increased seedling growth and/or suppressed rice blast disease in greenhouse-grown plants of the cultivars Super Basmati and Azucena, but each cultivar responded to different subsets of the bacteria. In the cv Super Basmati, increased blast resistance was correlated with the production of siderophores by the rhizobacteria. Several strains inhibited the growth of the causative agent of rice blast disease, the fungal pathogen Magnaporthe grisea, in an in vitro dual culture assay. Direct bioantagonism was correlated with disease resistance in Super Basmati, but not in Azucena, and direct antagonism as a cause for the reduced disease incidence is also unlikely since no epiphytic colonisation of leaves was detected. Rhizosphere colonisation by the bacteria in plants grown in sterile sand was correlated with disease resistance in Super Basmati, but not in Azucena. As well as the differences in strains that protected each cv against blast disease, we also found that there were differences in the ability of some strains to protect plants against blast depending on soil type. Hence, there are complex interactions between rhizobacteria and rice plants with respect to biocontrol of rice blast disease, dependent upon both rice cv and soil type. The identity of strains that promoted high levels of disease protection, including three that performed well across all plant cultivars and growth conditions, was determined by 16S rRNA gene sequencing

    15N NMR study of a mixture of uniformly labeled tRNAs

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    15N NMR spectra were taken of 15N-enriched tRNA extracted from bakers yeast; ammonium sulfate was used as a nitrogen source. The increase in the degree of denaturation of tRNA, which occurs with increase in temperature from 30 degrees C to 70 degrees C, resulted in no large changes in 15N chemical shifts at acidic and neutral pH but quite pronounced changes in proton-15N nuclear Overhauser effects

    Keeping it in the family:transgenerational memories of plant defence

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    Plants possess a sophisticated array of systems with which to sense and respond to their internal and external environment. Biological changes triggered by such systems represent examples of phenotypic plasticity. One aspect of phenotypic plasticity that has recently emerged is transgenerational priming of plant defence responses – the persistence of induced resistance responses across generations. There has been a recent surge in interest in epigenetic mechanisms as a basis for phenotypic plasticity, including the ability for such epigenetic changes to be inherited across generations. In this review, we focus on the evidence that attack by pests and disease can stimulate plant defence responses that increase levels of resistance not only in attacked plants, but in their offspring, and discuss mechanisms by which environmental stress signals can be inherited. Finally, we consider the implications of transgenerational defence responses for plants in natural and agricultural systems

    Towards Real-Time Information Processing of Sensor Network Data using Computationally Efficient Multi-output Gaussian Processes

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    In this paper, we describe a novel, computationally efficient algorithm that facilitates the autonomous acquisition of readings from sensor networks (deciding when and which sensor to acquire readings from at any time), and which can, with minimal domain knowledge, perform a range of information processing tasks including modelling the accuracy of the sensor readings, predicting the value of missing sensor readings, and predicting how the monitored environmental variables will evolve into the future. Our motivating scenario is the need to provide situational awareness support to first responders at the scene of a large scale incident, and to this end, we describe a novel iterative formulation of a multi-output Gaussian process that can build and exploit a probabilistic model of the environmental variables being measured (including the correlations and delays that exist between them). We validate our approach using data collected from a network of weather sensors located on the south coast of England

    Information Agents for Pervasive Sensor Networks

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    In this paper, we describe an information agent, that resides on a mobile computer or personal digital assistant (PDA), that can autonomously acquire sensor readings from pervasive sensor networks (deciding when and which sensor to acquire readings from at any time). Moreover, it can perform a range of information processing tasks including modelling the accuracy of the sensor readings, predicting the value of missing sensor readings, and predicting how the monitored environmental parameters will evolve into the future. Our motivating scenario is the need to provide situational awareness support to first responders at the scene of a large scale incident, and we describe how we use an iterative formulation of a multi-output Gaussian process to build a probabilistic model of the environmental parameters being measured by local sensors, and the correlations and delays that exist between them. We validate our approach using data collected from a network of weather sensors located on the south coast of England
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