We construct a simple SO(10) SUSY GUT with D3 family symmetry and low energy R-parity. The model describes fermion mass matrices with 14 parameters and gives excellent fits to 20 observable masses ...and mixing angles in both quark and lepton sectors, giving 6 predictions. Bi-large neutrino mixing is obtained with hierarchical quark and lepton Yukawa matrices; thus avoiding the possibility of large lepton flavor violation. The model naturally predicts small 1–3 neutrino mixing, sinθ13≃0.05, and a CP violating phase δ close to π/2. Among other interesting predictions is a tiny effective Majorana mass for neutrinoless double-beta decay. Leptogenesis is also possible with the decay of the lightest right-handed neutrino giving an acceptable CP violating asymmetry ε1 of order 10−6, and with the correct sign for the resultant baryon asymmetry. Note, similar models with the non-Abelian symmetry groups SU(2) or D4, instead of D3, can be constructed.
In this Letter we present a “natural” framework for obtaining bi-large neutrino mixing incorporating the Frampton–Glashow–Yanagida neutrino mass matrix ansatz. We show that an SU(2)×U(1) family ...symmetry can provide the desired FGY neutrino mass ansatz in a minimal supersymmetric standard model. We also show how to obtain an approximate FGY ansatz in an SO(10) SUSY GUT. In this context, the same SU(2)×U(1) family symmetry also generates the hierarchy of fermion masses as well as ameliorating SUSY flavor problems.
A
bstract
We engineer compact SU(5) Grand Unified Theories in F-theory in which GUT-breaking is achieved by a discrete Wilson line. Because the internal gauge field is flat, these models avoid the ...high scale threshold corrections associated with hypercharge flux. Along the way, we exemplify the ‘local-to-global’ approach in F-theory model building and demonstrate how the Tate divisor formalism can be used to address several challenges of extending local models to global ones. These include in particular the construction of
G
-fluxes that extend non-inherited bundles and the engineering of U(1) symmetries. We go beyond chirality computations and determine the precise (charged) massless spectrum, finding exactly three families of quarks and leptons but excessive doublet and/or triplet pairs in the Higgs sector (depending on the example) and vector-like exotics descending from the adjoint of SU(5)
GUT
. Understanding why vector-like pairs persist in the Higgs sector without an obvious symmetry to protect them may shed light on new solutions to the
μ
problem in F-theory GUTs.
The optimal method for diagnosing ventilator-associated pneumonia (VAP) is controversial and its effect on reported incidence uncertain. This study aimed to model the impact of using either ...endotracheal aspirate or bronchoalveolar lavage on the reported incidence of pneumonia and then to test effects suggested from theoretical modelling in clinical practice.
A three-part single-centre study was undertaken. First, diagnostic performance of aspirate and lavage were compared using paired samples from 53 patients with suspected VAP. Secondly, infection surveillance data were used to model the potential effect on pneumonia incidence and antibiotic use of using exclusively aspirate or lavage to investigate suspected pneumonia (643 patients; 110 clinically suspected pneumonia episodes). Thirdly, a practice change initiative was undertaken to increase lavage use; pneumonia incidence and antibiotic use were compared for the 12 months before and after the change.
Aspirate overdiagnosed VAP compared with lavage (89% vs 21% of clinically suspected cases, p<0.0001). Modelling suggested that changing from exclusive aspirate to lavage diagnosis would decrease reported pneumonia incidence by 76% (95% CI 67% to 87%) and antibiotic use by 30% (95% CI 20% to 42%). After the practice change initiative, lavage use increased from 37% to 58%. Although clinically suspected pneumonia incidence was unchanged, microbiologically confirmed VAP decreased from 18 to 9 cases per 1000 ventilator days (p = 0.001; relative risk reduction 0.61 (95% CI 0.46 to 0.82)), and mean antibiotic use fell from 9.1 to 7.2 antibiotic days (21% decrease, p = 0.08).
Diagnostic technique impacts significantly on reported VAP incidence and potentially on antibiotic use.
PDF
