795 research outputs found

    RNA-seq reveals post-transcriptional regulation of Drosophila insulin-like peptide dilp8 and the neuropeptide-like precursor Nplp2 by the exoribonuclease Pacman/XRN1

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    Ribonucleases are critically important in many cellular and developmental processes and defects in their expression are associated with human disease. Pacman/XRN1 is a highly conserved cytoplasmic exoribonuclease which degrades RNAs in a 5' - 3' direction. In Drosophila, null mutations in pacman result in small imaginal discs, a delay in onset of pupariation and lethality during the early pupal stage. In this paper, we have used RNA-seq in a genome-wide search for mRNAs misregulated in pacman null wing imaginal discs. Only 4.2% of genes are misregulated ±>2-fold in pacman null mutants compared to controls, in line with previous work showing that Pacman has specificity for particular mRNAs. Further analysis of the most upregulated mRNAs showed that Pacman post-transcriptionally regulates the expression of the secreted insulin-like peptide Dilp8. Dilp8 is related to human IGF-1, and has been shown to co-ordinate tissue growth with developmental timing in Drosophila. The increased expression of Dilp8 is consistent with the developmental delay seen in pacman null mutants. Our analysis, together with our previous results, show that the normal role of this exoribonuclease in imaginal discs is to suppress the expression of transcripts that are crucial in apoptosis and growth control during normal development

    Oxygen-stripes in La0.5Ca0.5MnO3 from ab initio calculations

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    We investigate the electronic, magnetic and orbital properties of La0.5Ca0.5MnO3 perovskite by means of an ab initio electronic structure calculation within the Hartree-Fock approximation. Using the experimental crystal structure reported by Radaelli et al. [Phys. Rev B 55, 3015 (1997)], we find a charge-ordering stripe-like ground state. The periodicity of the stripes, and the insulating CE-type magnetic structure are in agreement with neutron x-ray and electron diffraction experiments. However, the detailed structure is more complex than that envisaged by simple models of charge and orbital order on Mn d-levels alone, and is better described as a charge-density wave of oxygen holes, coupled to the Mn spin/orbital order.Comment: 4 pages, 3 figures. Version accepted for publication in PR

    Continuum variational and diffusion quantum Monte Carlo calculations

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    This topical review describes the methodology of continuum variational and diffusion quantum Monte Carlo calculations. These stochastic methods are based on many-body wave functions and are capable of achieving very high accuracy. The algorithms are intrinsically parallel and well-suited to petascale computers, and the computational cost scales as a polynomial of the number of particles. A guide to the systems and topics which have been investigated using these methods is given. The bulk of the article is devoted to an overview of the basic quantum Monte Carlo methods, the forms and optimisation of wave functions, performing calculations within periodic boundary conditions, using pseudopotentials, excited-state calculations, sources of calculational inaccuracy, and calculating energy differences and forces

    Silver Coated Bioactive Glass Particles for Wound Healing Applications

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    Hench and colleagues discovered that bone could bond chemically to certain glass compositions in 1969 [1]. This group of glasses is known as bioactive glasses [1]. Some special compositions of bioactive glasses will bond to soft tissues as well as bone [1]. One of the important characteristics of bioactive glasses is their ability to release beneficial ions such as Ca2+, Na+, Zn2+, Sr2+, and PO 43- in the body, which promote self-healing [2]. Bioactive glasses generally contain much less glass former (e.g., SiO2, B2O3 etc.) than conventional glasses [3]. Network modifiers encourage the formation of Non-Bridging Oxygens (NBO) groups. These NBO groups decrease aqueous durability and increase bioactivity [4]. © 2012 IEEE

    Quantum Monte Carlo study of the Ne atom and the Ne+ ion

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    We report all-electron and pseudopotential calculations of the ground-stateenergies of the neutral Ne atom and the Ne+ ion using the variational and diffusion quantum Monte Carlo (DMC) methods. We investigate different levels of Slater-Jastrow trial wave function: (i) using Hartree-Fock orbitals, (ii) using orbitals optimized within a Monte Carlo procedure in the presence of a Jastrow factor, and (iii) including backflow correlations in the wave function. Small reductions in the total energy are obtained by optimizing the orbitals, while more significant reductions are obtained by incorporating backflow correlations. We study the finite-time-step and fixed-node biases in the DMC energy and show that there is a strong tendency for these errors to cancel when the first ionization potential (IP) is calculated. DMC gives highly accurate values for the IP of Ne at all the levels of trial wave function that we have considered

    A feasibility study of auricular therapy and self-administered acupressure for insomnia following cancer treatment

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    Introduction: Many cancer patients experience sleeping difficulties which can persist several years after the completion of cancer treatment. Previous research suggests that acupuncture, and variants of acupuncture (acupressure, auricular therapy) may be effective treatment options for sleep disturbance. However, current evidence is limited for cancer patients. Methods: Feasibility study with 3 arms. Seven cancer patients with insomnia randomised to receive either auricular therapy (attaching semen vaccariae seeds to ear acupoints) (n = 4), self-acupressure (n= 1) or no treatment (n= 2). Participants assigned to receive auricular therapy or self-acupressure stimulated the acupoints each night an hour before retiring to bed. The duration of participant involvement was 5 weeks. Subjective sleep quality was measured at baseline and post-treatment using the Pittsburgh sleep quality index (PSQI). The impact of treatment on concerns of importance to the participants themselves was measured using the measure yourself concerns and wellbeing (MYCaW). Each participant also completed a treatment log book. Results: All participants completed their treatment. All auricular therapy and self-acupressure participants recorded clinically significant improvements in global PSQI scores. In the auricular therapy arm mean global PSQI reduced from 12.5 at baseline to 8 following completion of treatment. In the self-acupressure arm PSQI reduced from 15 to 11. While in the no treatment arm the mean PSQI score was 14.5 at both baseline and follow up. Conclusions: Despite the limited sample size, both auricular therapy and self-acupressure may represent potentially effective treatments for cancer patients with insomnia. The positive findings suggest further research is warranted into both treatment modalities.School of Nursin

    Silver Coated Bioactive Glass Particles for Wound Healing Applications

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    Bioactive glass particles (0.42SiO2-0.15CaO-0.23Na 2O-0.20ZnO) of varying size (\u3c90 \u3eμm and 425-850 μm) were synthesized and coated with silver (Ag) to produce Ag coated particles (PAg). These were compared against the uncoated analogous particles (Pcon.). Surface area analysis determined that Ag coating of the glass particles resulted in increased the surface area from 2.90 to 9.12 m2/g (90 μm) and 1.09-7.71 m2/g (425-850 μm). Scanning electron microscopy determined that the Ag coating remained at the surface and there was little diffusion through the bulk. Antibacterial (Escherichia coli - 13 mm and Staphylococcus epidermidis - 12 mm) and antifungal testing (Candida albicans - 7.7 mm) determined that small Ag-coated glass particles exhibited the largest inhibition zones compared to uncoated particles. pH analysis determined an overall higher pH consider in the smaller particles, where after 24 h the large uncoated and Ag coated particles were 8.27 and 8.74 respectively, while the smaller uncoated and Ag coated particles attained pH values of 9.63 and 9.35 respectively. © Springer Science+Business Media, LLC 2012

    The super-recogniser advantage extends to the detection of hyper-realistic face masks

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    Hyper-realistic silicone masks provide a viable route to identity fraud. Over the last decade, more than 40 known criminal acts have been committed by perpetrators using this type of disguise. With the increasing availability and bespoke sophistication of these masks, research must now focus on ways to enhance their detection. In this study, we investigate whether super-recognisers (SRs), people who excel at identity recognition, are more likely to detect this type of fraud, in comparison to typical-recogniser controls. Across three tasks, we examined mask detection rates in the absence of a pre-task prompt (covert task), and again after making participants aware of their use in criminal settings (explicit task). Finally, participants were asked to indicate which aspects of the masks could support their detection (regions of interest task). The findings show an SR advantage for the detection of hyper-realistic masks across the covert and explicit mask detection tasks. In addition, the eye, mouth, and nose regions appear to be particularly indicative of the presence of a mask. The lack of natural skin texture, proportional features, expressiveness, and asymmetry are also salient cues. The theoretical and applied implications of these findings are discussed

    Xrn1/Pacman affects apoptosis and regulates expression of hid and reaper

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    Programmed cell death, or apoptosis, is a highly conserved cellular process that is crucial for tissue homeostasis under normal development as well as environmental stress. Misregulation of apoptosis is linked to many developmental defects and diseases such as tumour formation, autoimmune diseases and neurological disorders. In this paper, we show a novel role for the exoribonuclease Pacman/Xrn1 in regulating apoptosis. Using Drosophila wing imaginal discs as a model system, we demonstrate that a null mutation in pacman results in small imaginal discs as well as lethality during pupation. Mutant wing discs show an increase in the number of cells undergoing apoptosis, especially in the wing pouch area. Compensatory proliferation also occurs in these mutant discs, but this is insufficient to compensate for the concurrent increase in apoptosis. The phenotypic effects of the pacman null mutation are rescued by a deletion that removes one copy of each of the pro-apoptotic genes reaper, hid and grim, demonstrating that pacman acts through this pathway. The null pacman mutation also results in a significant increase in the expression of the pro-apoptotic mRNAs, hid and reaper, with this increase mostly occurring at the post-transcriptional level, suggesting that Pacman normally targets these mRNAs for degradation. Our results uncover a novel function for the conserved exoribonuclease Pacman and suggest that this exoribonuclease is important in the regulation of apoptosis in other organisms
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