11,372 research outputs found

    Magic Neutrino Mass Matrix and the Bjorken-Harrison-Scott Parameterization

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    Observed neutrino mixing can be described by a tribimaximal MNS matrix. The resulting neutrino mass matrix in the basis of a diagonal charged lepton mass matrix is both 2-3 symmetric and magic. By a magic matrix, I mean one whose row sums and column sums are all identical. I study what happens if 2-3 symmetry is broken but the magic symmetry is kept intact. In that case, the mixing matrix is parameterized by a single complex parameter Ue3U_{e3}, in a form discussed recently by Bjorken, Harrison, and Scott.Comment: Two references added. To appear in Physics Letters

    Dark Scalar Doublets and Neutrino Tribimaximal Mixing from A_4 Symmetry

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    In the context of A_4 symmetry, neutrino tribimaximal mixing is achieved through the breaking of A_4 to Z_3 (Z_2) in the charged-lepton (neutrino) sector respectively. The implied vacuum misalignment of the (1,1,1) and (1,0,0) directions in A_4 space is a difficult technical problem, and cannot be treated without many auxiliary fields and symmetries (and perhaps extra dimensions). It is pointed out here that an alternative scenario exists with A_4 alone and no redundant fields, if neutrino masses are "scotogenic", i.e. radiatively induced by dark scalar doublets as recently proposed.Comment: 8 pages, 2 figures, 1 reference and 1 paragraph adde

    Thoracic and lumbar vertebral bone mineral density changes in a natural occuring dog model of diffuse idiopathic skeletal hyperostosis

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    Ankylosing spinal disorders can be associated with alterations in vertebral bone mineral density (BMD). There is however controversy about vertebral BMD in patients wuse idiopathic skeletal hyperostosis (DISH). DISH in Boxer dogs has been considered a natural occurring disease model for DISH in people. The purpose of this study was to compare vertebral BMD between Boxers with and without DISH. Fifty-nine Boxers with (n=30) or without (n=29) DISH that underwent computed tomography were included. Vertebral BMD was calculated for each thoracic and lumbar vertebra by using an earlier reported and validated protocol. For each vertebral body, a region of interest was drawn on the axial computed tomographic images at three separate locations: immediately inferior to the superior end plate, in the middle of the vertebral body, and superior to the inferior end plate. Values from the three axial slices were averaged to give a mean Hounsfield Unit value for each vertebral body. Univariate statistical analysis was performed to identify factors to be included in a multivariate model. The multivariate model including all dogs demonstrated that vertebral DISH status (Coefficient 24.63; 95% CI 16.07 to 33.19; p < 0.001), lumbar vertebrae (Coefficient -17.25; 95% CI -23.42 to -11.09; p < 0.01), and to a lesser extent higher age (Coefficient -0.56; 95% CI -1.07 to -0.05; p = 0.03) were significant predictors for vertebral BMD. When the multivariate model was repeated using only dogs with DISH, vertebral DISH status (Coefficient 20.67; 95% CI, 10.98 to 30.37; p < 0.001) and lumbar anatomical region (Coefficient -38.24; 95% CI, -47.75 to -28.73; p < 0.001) were again predictors for vertebral BMD but age was not. The results of this study indicate that DISH can be associated with decreased vertebral BMD. Further studies are necessary to evaluate the clinical importance and pathophysiology of this finding

    Teacher and student intrinsic motivation in project-based learning

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    In this study we examined the relationship between teacher and student intrinsic motivation in project-based learning. The participants were 126 Hong Kong secondary school teachers and their 631 students who completed evaluation questionnaires after a semester-long project-based learning program. Both teachers and students were asked to indicate their motivation in the program, and students were also asked to report the instructional support they received from their teachers. The results of hierarchical linear modeling analyses showed that teacher intrinsic motivation predicted student intrinsic motivation directly as well as indirectly through the mediation of instructional support. When teachers reported higher intrinsic motivation in the program, their students tended to perceive receiving more support from them and to report higher intrinsic motivation in the learning experience. © Springer Science+Business Media B.V. 2008.postprin

    eXCloud: Transparent runtime support for scaling mobile applications in cloud

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    Cloud computing augments applications with ease-of-access to the enormous resources on the Internet. Combined with mobile computing technologies, mobile applications can exploit the Cloud everywhere by statically distributing code segments or dynamically migrating running processes onto cloud services. Existing migration techniques are however too coarse-grained for mobile devices, so the overheads often offset the benefits of migration. To build a truly elastic mobile cloud computing infrastructure, we introduce eXCloud (eXtensible Cloud) - a middleware system with multi-level mobility support, ranging from as coarse as a VM instance to as fine as a runtime stack frame, and allows resources to be integrated and used dynamically. In eXCloud, a stack-on-demand (SOD) approach is used to support computation mobility throughout the mobile cloud environment. The approach is fully adaptive, goal-driven and transparent. By downward task migration, applications running on the cloud nodes can exploit or take control of special resources in mobile devices such as GPS and cameras. With a restorable MPI layer, task migrations of MPI parallel programs can happen between cloud nodes or be initiated from a mobile device. Our evaluation shows that SOD outperforms several existing migration mechanisms in terms of migration overhead and latency. All our techniques result in better resource utilization through task migrations among cloud nodes and mobile nodes.published_or_final_versionThe 2011 International Conference on Cloud and Service Computing (CSC), Hong Kong, China, 12-14 December 2011. In Proceedings of CSC, 2011, p. 103-11

    Laryngological presentations and patient-reported outcome measures in Ehlers-Danlos syndrome

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    OBJECTIVE: This study aimed to characterise the laryngological presentations of Ehlers–Danlos syndrome and conduct a preliminary exploration of patient-reported outcome measures. METHODS: This paper describes a retrospective case series of patients with Ehlers–Danlos syndrome seen by the senior author between 2005 and 2019. A literature review was conducted to summarise the existing findings. RESULTS: Twenty-one patients met the inclusion criteria. All reported symptoms were grouped; this showed that swallowing, voice and hyolaryngeal skeletal complex problems were commonest. Patient-reported outcome measures were available for eight patients, which showed large variations in: the Reflux Severity Index (median = 25.5; range = 0–33), Eating Assessment Tool score (median = 21.5; range = 0–35) and Voice Handicap Index (median = 21.5; range = 0–104). Twelve studies met our literature review inclusion criteria, involving at least 91 patients with laryngological presentations of Ehlers–Danlos syndrome. CONCLUSION: Ehlers–Danlos syndrome patients experience musculoskeletal issues, which in the throat manifest as hyolaryngeal skeletal complex problems. Future studies with larger patient numbers are required to validate laryngological patient-reported outcome measure tools in Ehlers–Danlos syndrome

    FXN promoter silencing in the humanized mouse model of Friedreich Ataxia

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    Background - Friedreich ataxia is caused by an expanded GAA triplet-repeat sequence in intron 1 of the FXN gene that results in epigenetic silencing of the FXN promoter. This silencing mechanism is seen in patient-derived lymphoblastoid cells but it remains unknown if it is a widespread phenomenon affecting multiple cell types and tissues. Methodology / Principal Findings - The humanized mouse model of Friedreich ataxia (YG8sR), which carries a single transgenic insert of the human FXN gene with an expanded GAA triplet-repeat in intron 1, is deficient for FXN transcript when compared to an isogenic transgenic mouse lacking the expanded repeat (Y47R). We found that in YG8sR the deficiency of FXN transcript extended both upstream and downstream of the expanded GAA triplet-repeat, suggestive of deficient transcriptional initiation. This pattern of deficiency was seen in all tissues tested, irrespective of whether they are known to be affected or spared in disease pathogenesis, in both neuronal and non-neuronal tissues, and in cultured primary fibroblasts. FXN promoter function was directly measured via metabolic labeling of newly synthesized transcripts in fibroblasts, which revealed that the YG8sR mouse was significantly deficient in transcriptional initiation compared to the Y47R mouse. Conclusions / Significance- Deficient transcriptional initiation accounts for FXN transcriptional deficiency in the humanized mouse model of Friedreich ataxia, similar to patient-derived cells, and the mechanism underlying promoter silencing in Friedreich ataxia is widespread across multiple cell types and tissues.This research was supported by grants from the National Institutes of Health (R01 NS072418), and the Muscular Dystrophy Association to S.I.B. Y.K.C. is supported by a postdoctoral research fellowship from the Million Dollar Bike Ride Grant Program of the Orphan Disease Center at University of Pennsylvania. T.T.H. was supported by the American College of Medical Genetics Foundation. A.C.P. and M.G.M. were supported by the SURE and OSCTR programs at OUHSC, respectively

    Intrinsic Deviation from the Tri-bimaximal Neutrino Mixing in a Class of A_4 Flavor Models

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    It is well known that the tri-bimaximal neutrino mixing pattern V_0 can be derived from a class of flavor models with the non-Abelian A_4 symmetry. We point out that small corrections to V_0, which are inherent in the A_4 models and arise from both the charged-lepton and neutrino sectors, have been omitted in the previous works. We show that such corrections may lead the 3 \times 3 neutrino mixing matrix V to a non-unitary deviation from V_0, but they cannot result in a nonzero value of \theta_13 or any new CP-violating phases. Current experimental constraints on the unitarity of V allow us to constrain the model parameters to some extent.Comment: 11 pages, no figures; a reference added, accepted for publication in Phys. Lett.
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