874 research outputs found

    Where does Flavour Mixing come from?

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    We argue that flavour mixing, both in the quark and charged lepton sector, is basically determined by the lightest family mass generation mechanism. So, in the chiral symmetry limit when the up and down quark masses vanish, all the quark mixing angles vanish. This mechanism is not dependent on the number of quark-lepton families nor on any ``vertical'' symmetry structure, unifying quarks and leptons inside a family as in Grand Unified Theories. Together with a hypothesis of maximal CP violation, the model leads to a completely predictive ansatz for all the CKM matrix elements in terms of the quark masses. Some implications for neutrino masses and oscillations are briefly discussed.Comment: 13 page LaTeX file, minor changes in fourth paragraph of Conclusion and in Reference

    Formal change impact analyses for emulated control software

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    Processor emulators are a software tool for allowing legacy computer programs to be executed on a modern processor. In the past emulators have been used in trivial applications such as maintenance of video games. Now, however, processor emulation is being applied to safety-critical control systems, including military avionics. These applications demand utmost guarantees of correctness, but no verification techniques exist for proving that an emulated system preserves the original system’s functional and timing properties. Here we show how this can be done by combining concepts previously used for reasoning about real-time program compilation, coupled with an understanding of the new and old software architectures. In particular, we show how both the old and new systems can be given a common semantics, thus allowing their behaviours to be compared directly

    Ethical issues in neuroimaging health research:an IPA study with research participants

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    Neuroimaging is increasingly used to understand conditions like stroke and epilepsy. However, there is growing recognition that neuroimaging can raise ethical issues. We used interpretative phenomenological analysis to analyse interview data pre-and post-scan to explore these ethical issues. Findings show participants can become anxious prior to scanning and the protocol for managing incidental findings is unclear. Participants lacked a frame of reference to contextualize their expectations and often drew on medical narratives. Recommendations to reduce anxiety include dialogue between researcher and participant to clarify understanding during consent and the use of a `virtual tour' of the neuroimaging experience

    On the Cauchy problem for the debar operator

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    We present new results concerning the solvability, of lack thereof, in the Cauchy problem for the debar operator, with initial values assigned on a weakly pseudoconvex hypersurface, and provide illustrative examples.Comment: This is the final version, which is appearing in Arkiv foer Mathemati

    Women, anger, and aggression an interpretative phenomenological analysis

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    This study reports a qualitative phenomenological investigation of anger and anger-related aggression in the context of the lives of individual women. Semistructured interviews with five women are analyzed using interpretative phenomenological analysis. This inductive approach aims to capture the richness and complexity of the lived experience of emotional life. In particular, it draws attention to the context-dependent and relational dimension of angry feelings and aggressive behavior. Three analytic themes are presented here: the subjective experience of anger, which includes the perceptual confusion and bodily change felt by the women when angry, crying, and the presence of multiple emotions; the forms and contexts of aggression, paying particular attention to the range of aggressive strategies used; and anger as moral judgment, in particular perceptions of injustice and unfairness. The authors conclude by examining the analytic observations in light of phenomenological thinking

    Minimal Mixing of Quarks and Leptons in the SU(3) Theory of Flavour

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    We argue that flavour mixing, both in the quark and lepton sector, follows the minimal mixing pattern, according to which the whole of this mixing is basically determined by the physical mass generation for the first family of fermions. So, in the chiral symmetry limit when the masses of the lightest (uu and dd) quarks vanish, all the quark mixing angles vanish. This minimal pattern is shown to fit extremely well the already established CKM matrix elements and to give fairly distinctive predictions for the as yet poorly known ones. Remarkably, together with generically small quark mixing, it also leads to large neutrino mixing, provided that neutrino masses appear through the ordinary ``see-saw'' mechanism. It is natural to think that this minimal flavour mixing pattern presupposes some underlying family symmetry, treating families of quarks and leptons in a special way. Indeed, we have found a local chiral SU(3)FSU(3)_{F} family symmetry model which leads, through its dominant symmetry breaking vacuum configuration, to a natural realization of the proposed minimal mechanism. It can also naturally generate the quark and lepton mass hierarchies. Furthermore spontaneous CP violation is possible, leading to a maximal CP violating phase δ=π2\delta =\frac{\pi}{2}, in the framework of the MSSM extended by a high-scale SU(3)FSU(3)_{F} chiral family symmetry.Comment: 52 pages, LaTex, no figures; some typos corrected; journal versio

    C9ORF72 patient-derived endothelial cells drive blood-brain barrier disruption and contribute to neurotoxicity

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    The blood-brain barrier (BBB) serves as a highly intricate and dynamic interface connecting the brain and the bloodstream, playing a vital role in maintaining brain homeostasis. BBB dysfunction has been associated with multiple neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS); however, the role of the BBB in neurodegeneration is understudied. We developed an ALS patient-derived model of the BBB by using cells derived from 5 patient donors carrying C9ORF72 mutations. Brain microvascular endothelial-like cells (BMEC-like cells) derived from C9ORF72-ALS patients showed altered gene expression, compromised barrier integrity, and increased P-glycoprotein transporter activity. In addition, mitochondrial metabolic tests demonstrated that C9ORF72-ALS BMECs display a significant decrease in basal glycolysis accompanied by increased basal and ATP-linked respiration. Moreover, our study reveals that C9-ALS derived astrocytes can further affect BMECs function and affect the expression of the glucose transporter Glut-1. Finally, C9ORF72 patient-derived BMECs form leaky barriers through a cell-autonomous mechanism and have neurotoxic properties towards motor neurons

    Conforming to accreditation in Iranian hospitals

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    This paper examines the operation of an accreditation programme for hospitals in Iran. It explores the process of accreditation as a regulatory control system and analyses hospitals’ responses to this type of control. We draw on the notion of steering and argue that the accreditation system is transactional in nature. Our findings show that hospitals conform to the scheme, although they also resist some of its requirements. On a wider policy level, we suggest that accreditations offer the accreditor the opportunity to impact on how activities are undertaken, but hospitals require incentives in order to make the necessary organisational changes

    Cosmological distance indicators

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    We review three distance measurement techniques beyond the local universe: (1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and (3) HI intensity mapping. We describe the principles and theory behind each method, the ingredients needed for measuring such distances, the current observational results, and future prospects. Time delays from strongly lensed quasars currently provide constraints on H0H_0 with < 4% uncertainty, and with 1% within reach from ongoing surveys and efforts. Recent exciting discoveries of strongly lensed supernovae hold great promise for time-delay cosmography. BAO features have been detected in redshift surveys up to z <~ 0.8 with galaxies and z ~ 2 with Ly-α\alpha forest, providing precise distance measurements and H0H_0 with < 2% uncertainty in flat Λ\LambdaCDM. Future BAO surveys will probe the distance scale with percent-level precision. HI intensity mapping has great potential to map BAO distances at z ~ 0.8 and beyond with precisions of a few percent. The next years ahead will be exciting as various cosmological probes reach 1% uncertainty in determining H0H_0, to assess the current tension in H0H_0 measurements that could indicate new physics.Comment: Review article accepted for publication in Space Science Reviews (Springer), 45 pages, 10 figures. Chapter of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Ag

    Diverse Durham collection phages demonstrate complex BREX defence responses

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    Bacteriophages (phages) outnumber bacteria ten-to-one and cause infections at a rate of 1025 per second. The ability of phages to reduce bacterial populations makes them attractive alternative antibacterials for use in combating the rise in antimicrobial resistance. This effort may be hindered due to bacterial defenses such as Bacteriophage Exclusion (BREX) that have arisen from the constant evolutionary battle between bacteria and phages. For phages to be widely accepted as therapeutics in Western medicine, more must be understood about bacteria–phage interactions and the outcomes of bacterial phage defense. Here, we present the annotated genomes of 12 novel bacteriophage species isolated from water sources in Durham, UK, during undergraduate practical classes. The collection includes diverse species from across known phylogenetic groups. Comparative analyses of two novel phages from the collection suggest they may be founding members of a new genus. Using this Durham phage collection, we determined that particular BREX defense systems were likely to confer a varied degree of resistance against an invading phage. We concluded that the number of BREX target motifs encoded in the phage genome was not proportional to the degree of susceptibility
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