Postembryonic RNAi in Heterorhabditis bacteriophora: a nematode insect parasite and host for insect pathogenic symbionts

Background: Heterorhabditis bacteriophora is applied throughout the world for the biological control of insects and is an animal model to study interspecies interactions, e.g. mutualism, parasitism and vector-borne disease. H. bacteriophora nematodes are mutually associated with the insect pathogen, Photorhabdus luminescens. The developmentally arrested infective juvenile (IJ) stage nematode (vector) specifically transmits Photorhabdus luminescens bacteria (pathogen) in its gut mucosa to the haemocoel of insects (host). The nematode vector and pathogen alone are not known to cause insect disease. RNA interference is an excellent reverse genetic tool to study gene function in C. elegans, and it would be useful in H. bacteriophora to exploit the H. bacteriophora genome project, currently in progress. Results: Soaking L1 stage H. bacteriophora with seven dsRNAs of genes whose C. elegans orthologs had severe RNAi phenotypes resulted in highly penetrant and obvious developmental and reproductive abnormalities. The efficacy of postembryonic double strand RNA interference (RNAi) was evident by abnormal gonad morphology and sterility of adult H. bacteriophora and C. elegans presumable due to defects in germ cell proliferation and gonad development. The penetrance of RNAi phenotypes in H. bacteriophora was high for five genes (87-100%; Hba-cct-2, Hba-daf-21, Hba-icd-1; Hba-nol-5, and Hba-W01G7.3) and moderate for two genes (usually 30-50%; Hba-rack-1 and Hba-arf-1). RNAi of three additional C. elegans orthologs for which RNAi phenotypes were not previously detected in C. elegans, also did not result in any apparent phenotypes in H. bacteriophora. Specific and severe reduction in transcript levels in RNAi treated L1s was determined by quantitative real-time RT-PCR. These results suggest that postembryonic RNAi by soaking is potent and specific. Conclusion: Although RNAi is conserved in animals and plants, RNAi using long dsRNA is not. These results demonstrate that RNAi can be used effectively in H. bacteriophora and can be applied for analyses of nematode genes involved in symbiosis and parasitism. It is likely that RNAi will be an important tool for functional genomics utilizing the high quality draft H. bacteriophora genome sequence

Credit Ratings as Coordination Mechanisms

In this paper, we provide a novel rationale for credit ratings. The rationale that we propose is that credit ratings can serve as a coordinating mechanism in situations where multiple equilibria can obtain. We show that credit ratings provide a "focal point" for firms and their investors. We explore the vital, but previously overlooked implicit contractual relationship between a credit rating agency and a firm. Credit ratings can help fix the desired equilibrium and as such play an economically meaningful role. Our model provides several empirical predictions and insights regarding the expected price impact of ratings changes, the discreteness in funding cost changes, and the effect of the focus of organizations on the efficacy of credit ratings.http://deepblue.lib.umich.edu/bitstream/2027.42/39841/3/wp457.pd

Fluorescence microscopy for the characterization of structural integrity

The absorption characteristics of light and the optical technique of fluorescence microscopy for enhancing metallographic interpretation are presented. Characterization of thermally sprayed coatings by optical microscopy suffers because of the tendency for misidentification of the microstructure produced by metallographic preparation. Gray scale, in bright field microscopy, is frequently the only means of differentiating the actual structural details of porosity, cracking, and debonding of coatings. Fluorescence microscopy is a technique that helps to distinguish the artifacts of metallographic preparation (pullout, cracking, debonding) from the microstructure of the specimen by color contrasting structural differences. Alternative instrumentation and the use of other dye systems are also discussed. The combination of epoxy vacuum infiltration with fluorescence microscopy to verify microstructural defects is an effective means to characterize advanced materials and to assess structural integrity

Credit Ratings as Coordination Mechanisms

In this paper, we provide a novel rationale for credit ratings. The rationale that we propose is that credit ratings can serve as a coordinating mechanism in situations where multiple equilibria can obtain. We show that credit ratings provide a "focal point" for firms and their investors. We explore the vital, but previously overlooked implicit contractual relationship between a credit rating agency and a firm. Credit ratings can help fix the desired equilibrium and as such play an economically meaningful role. Our model provides several empirical predictions and insights regarding the expected price impact of ratings changes, the discreteness in funding cost changes, and the effect of the focus of organizations on the efficacy of credit ratings.coordination, credit ratings, multiple equilibria

Preparation of urban land use inventories by machine processing of ERTS MSS data

Spectral classes of urban phenomena identified from Earth Resources Technology Satellite (ERTS) multispectral scanner data in Milwaukee included suburban inner city, industry, grassy (open area), road, wooded suburb, water cloud, and shadow. The Milwaukee spectral class statistics were used to classify the Chicago area, within the same ERTS frame, and similar results were achieved. In another ERTS frame, Marion County (Indianapolis) data were classified into similar classes. The Marion County ERTS study was supported by a land use classification of an area near downtown Indianapolis that utilized 12-band MSS data collected by aircraft from 3000 feet. The results of the ERTS analyses suggest that satellite data will be a useful tool for the urban planner for monitoring urban land use

Potential competitive effects on U.S. bank credit card lending from the proposed bifurcated application of Basel II

This paper analyzes the potential competitive effects of the proposed bifurcated application of Basel II capital regulations in the United States on bank credit card lending activities. For this purpose, the authors consider the Basel II regulations as stated in the June 2004 Basel Committee Framework Agreement. ; Also issued as Payment Cards Center Discussion Paper No. 05-21 ; Superseded by Working Paper 07-09Basel capital accord ; Credit cards

The South Dakota cooperative land use effort: A state level remote sensing demonstration project

Remote sensing technology can satisfy or make significant contributions toward satisfying many of the information needs of governmental natural resource planners and policy makers. Recognizing this potential, the South Dakota State Planning Bureau and the EROS Data Center together formulated the framework for an ongoing Land Use and Natural Resource Inventory and Information System Program. Statewide land use/land cover information is generated from LANDSAT digital data and high altitude photography. Many applications of the system are anticipated as it evolves and data are added from more conventional sources. The conceptualization, design, and implementation of the program are discussed

Quantum State Diffusion and Time Correlation Functions

In computing the spectra of quantum mechanical systems one encounters the Fourier transforms of time correlation functions, as given by the quantum regression theorem for systems described by master equations. Quantum state diffusion (QSD) gives a useful method of solving these problems by unraveling the master equation into stochastic trajectories; but there is no generally accepted definition of a time correlation function for a single QSD trajectory. In this paper we show how QSD can be used to calculate these spectra directly; by formally solving the equations which arise, we arrive at a natural definition for a two-time correlation function in QSD, which depends explicitly on both the stochastic noise of the particular trajectory and the time of measurement, and which agrees in the mean with the ensemble average definition of correlation functions.Comment: 16 pages standard LaTeX + 1 figure (uuencoded postscript) Numerous minor revisions and clarifications. To appear in J. Mod. Optic