1,111 research outputs found

    Spin-lattice Interaction in Ruby Measured by ESR in Uniaxially Stressed Crystals

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    Spin-lattice Hamiltonian determined for chromium ions in ruby single crystal

    A Clumpy Stellar Wind and Luminosity-Dependent Cyclotron Line Revealed by The First Suzaku Observation of the High-Mass X-ray Binary 4U 1538-522

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    We present results from the first Suzaku observation of the high-mass X-ray binary 4U 1538-522. The broad-band spectral coverage of Suzaku allows for a detailed spectral analysis, characterizing the cyclotron resonance scattering feature at 23.0±0.423.0 \pm 0.4 keV and the iron Kα\alpha line at 6.426±0.0086.426 \pm 0.008 keV, as well as placing limits on the strengths of the iron Kβ\beta line and the iron K edge. We track the evolution of the spectral parameters both in time and in luminosity, notably finding a significant positive correlation between cyclotron line energy and luminosity. A dip and spike in the lightcurve is shown to be associated with an order-of-magnitude increase in column density along the line of sight, as well as significant variation in the underlying continuum, implying the accretion of a overdense region of a clumpy stellar wind. We also present a phase-resolved analysis, with most spectral parameters of interest showing significant variation with phase. Notably, both the cyclotron line energy and the iron Kα\alpha line intensity vary significantly with phase, with the iron line intensity significantly out-of-phase with the pulse profile. We discuss the implications of these findings in the context of recent work in the areas of accretion column physics and cyclotron resonance scattering feature formation.Comment: 15 pages, 8 figures. Accepted to ApJ on 2 July 201

    Triggering and modulation of the host-parasite interplay by Echinococcus multilocularis: a review

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    As more facts emerge regarding the ways in which E. multilocularis-derived molecules trigger the host immune response and modulate the host-parasite interplay, it becomes possible to envisage how the parasite can survive and proliferate in its intermediate host, while in other hosts it dies out. Through effects on cells of both the innate and adaptive arms of the immune response, E. multilocularis can orchestrate a range of outcomes that are beneficial not only to the parasite, in terms of facilitating its intrahepatic proliferation and maturation, and thus life cycle over all, but also to its intermediate host, in limiting pathology. The present review deals with the role of metacestode surface molecules as well as excretory/secretory (E/S) metabolic products of the parasite in the modulation of the host responses such as to optimize its own surviva

    Adhesion and invasion of bovine endothelial cells by Neospora caninum

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    Neospora caninum is a recently identified coccidian parasite which was, until 1988, misdiagnosed as Toxoplasma gondii. It causes paralysis and death in dogs and neonatal mortality and abortion in cattle, sheep, goats and horses. The life-cycle of Neospora has not yet been elucidated. The only two stages identified so far are tissue cysts and intracellularly dividing tachyzoites. Very little is known about the biology of this species. We have set up a fluorescence-based adhesion/invasion assay in order to investigate the interaction of N. caninum tachyzoites with bovine aorta endothelial (BAE) cells in vitro. Treatment of both host cells and parasites with metabolic inhibitors determined the metabolic requirements for adhesion and invasion. Chemical and enzymatic modifications of parasite and endothelial cell surfaces were used in order to obtain information on the nature of cell surface components responsible for the interaction between parasite and host. Electron microscopical investigations defined the ultrastructural characteristics of the adhesion and invasion process, and provided information on the intracellular development of the parasite

    Strawberry varieties for Missouri

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    Cover title.Includes bibliographical references

    Performance of strawberry varieties in Missouri

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    The ethical beliefs and behaviours of Victorian fitness professionals

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    A survey based on those employed by Petitpas, Brewer, Rivera, and Van Raalte (1994), Pope, Tabachnick, and Keith-Spiegel (1987), Tabachnick, Keith-Spiegel, and Pope (1991), and Pope and Vetter (1992) was used to investigate the ethical beliefs and behaviours of Victorian fitness professionals. Although there is evidence that Victorian fitness professionals are knowledgeable about some general ethical principles, the results of this study suggest that there is some lack of consensus among Victorian fitness professionals about the ethical appropriateness of a number of complex issues relating to business practices, confidentiality, dual relationships, and personal and professional boundaries. The findings suggest there is a need to improve the professional and ethical education of fitness professionals and to develop comprehensive ethical principles and a code of conduct that is relevant to the individuals working in the Australian fitness profession

    Applications of Optical Control of Oligonucleotide and Protein Function

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    Optical regulation using light as an external trigger was applied to the control of biological processes with high spatio-temporal resolution. Photoremovable caging groups were site-specifically incorporated onto oligonucleotides and proteins to optically regulate their function in biological environments, typically for the photochemical control of gene expression. These caging group modifications enabled both OFF → ON and ON → OFF optochemical switches for important chemical biology tools. Oligonucleotides containing caging group modifications were synthesized to regulate nucleic acid function with light. Specifically, photocaged triplex-forming oligonucleotides were developed to optochemically control transcription in cell culture. Light-activated antagomirs were designed for the optical inhibition of miR-21 and miR-122 function in the regulation of endogenous microRNA activity. This technology was then applied to the study of miR-22 and miR-124 function in cortical neuron migration during cerebral corticogenesis. Splice-switching oligonucleotides were engineered to optically control mRNA splicing pathways in both human cells and zebrafish. The optical control of plasmid-based gene expression was demonstrated with a caged promoter, and applied to the photochemical activation of transcription in a live animal model. The caging of oligonucleotides was also applied to DNA computation in the production of optically controlled logic gates and amplification cycles, providing spatio-temporal control over hybridization cascades to add new functionality to DNA computation modules. These studies in DNA computation led to the development of novel biosensors for logic gate-based detection of specific micro RNA signatures in live cells. In addition, proteins were optically controlled through the site-specific installation of caging groups on amino acid side chains that are essential for protein function using unnatural amino acid mutagenesis in mammalian cells with an expanded genetic code. A caged lysine analogue was incorporated into T7 RNA polymerase to photochemically regulate transcription in the development of a light-activated synthetic gene network and light-triggered RNA interference. A light-activated Cas9 endonuclease was engineered through the installation of a caged lysine analogue to optically control CRISPR/Cas9 editing of both exogenous and endogenous genes. Lastly, a system for the incorporation of unnatural amino acids in zebrafish was studied in efforts to produce the first vertebrate species with an expanded genetic code

    NcGRA2 as a molecular target to assess the parasiticidal activity of toltrazuril against Neospora caninum

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    The treatment of Neospora caninum infection in the bovine host is still at an experimental stage. In contrast to the in vivo situation, a wide range of compounds have been intensively investigated in cell-culture-based assays. Tools to demonstrate efficacy of treatment have remained conventional including morphological and cell biological criteria. In this work, we present a molecular assay that allows the distinction between live and dead parasites. Live parasites can be detected by measuring the mRNA level of specific genes, making use of the specific mRNA available in live cells. The NcGra2 gene of N. caninum, which is known to be expressed in both tachyzoites and bradyzoites, was used to establish a quantitative real-time RT-PCR, for monitoring parasite viability. Validation of the system in vitro was achieved using Neospora-infected cells that had been treated for 2-20 days with 30μg/ml toltrazuril. NcGRA2-RT-real time PCR demonstrated that a 10-day toltrazuril-treatment exerted parasitostatic activity, as assessed by the presence of NcGRA2-transcripts, whereas after a 14-day treatment period no NcGRA2-transcripts were detected, showing that the parasites were no longer viable. Concurrently, extended culture for a period of 4 weeks in the absence of the drug following the 14-day toltrazuril treatment did not lead to further parasite proliferation, confirming the parasiticidal effect of the treatment. This assay has the potential to be widely used in the development of novel drugs against N. caninum, with a view to distinguishing between parasiticidal and parasitostatic efficacy of given compound

    The Value of PIC Cystography in Detecting De Novo and Residual Vesicoureteral Reflux after Dextranomer/Hyaluronic Acid Copolymer Injection

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    The endoscopic injection of Dx/HA in the management of vesicoureteral reflux (VUR) has become an accepted alternative to open surgery. In the current study we evaluated the value of cystography to detect de novo contralateral VUR in unilateral cases of VUR at the time of Dx/HA injection and correlated the findings of immediate post-Dx/HA injection cystography during the same anesthesia to 2-month postoperative VCUG to evaluate its ability to predict successful surgical outcomes. The current study aimed to evaluate whether an intraoperatively performed cystogram could replace postoperative studies. But a negative intraoperative cystogram correlates with the postoperative study in only 80%. Considering the 75–80% success rate of Dx/HA implantation, the addition of intraoperative cystograms cannot replace postoperative studies. In patients treated with unilateral VUR, PIC cystography can detect occult VUR and prevent postoperative contralateral new onset of VUR
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