86,680 research outputs found
Gauge coupling unification in E 6 F-theory GUTs with matter and bulk exotics from flux breaking
No full textWe consider gauge coupling unification in E 6 F-Theory Grand Unified Theories (GUTs) where E 6 is broken to the Standard Model (SM) gauge group using fluxes. In such models there are two types of exotics that can affect gauge coupling unification, namely matter exotics from the matter curves in the 27 dimensional representation of E 6 and the bulk exotics from the adjoint 78 dimensional representation of E 6. We explore the conditions required for either the complete or partial removal of bulk exotics from the low energy spectrum. In the latter case we shall show that (miraculously) gauge coupling unification may be possible even if there are bulk exotics at the TeV scale. Indeed in some cases it is necessary for bulk exotics to survive to the TeV scale in order to cancel the effects coming from other TeV scale matter exotics which would by themselves spoil gauge coupling unification. The combination of matter and bulk exotics in these cases can lead to precise gauge coupling unification which would not be possible with either type of exotics considered by themselves. The combination of matter and bulk exotics at the TeV scale represents a unique and striking signature of E 6 F-theory GUTs that can be tested at the LHC
Ejector performance influence on a solid oxide fuel cell anodic recirculation system
No full textThis work deals with the design and off-design performance evaluation of an anodic recirculation system based on ejector technology for solid oxide fuel cell hybrid applications.
The analysis presented here has been divided into three parts: (i) ejector design taking into account all the thermodynamic, fluid dynamic and chemical constraints, such as steam to carbon ratio (two ejector geometries have been considered: constant area mixing section, constant pressure mixing section); (ii) stand-alone ejector design and off-design performance analysis; (iii) influence on the whole hybrid system—SOFC, reformer, anode recirculation-design and off-design performance of the ejector primary flow conditions (hybrid system part-load conditions)
Gene transcription profiling in pollutant exposed mussels (Mytilus spp.) using a new low-density oligonucleotide microarray
No full textGauge mediation in F-theory GUT models
No full textWe study a simple framework for gauge-mediated supersymmetry breaking in local grand unified theory (GUT) models based on F-theory 7-branes and demonstrate that a mechanism for solving both the µ and µ/B_µ problems emerges in a natural way. In particular, a straightforward coupling of the messengers to the Higgs sector leads to a geometry which not only provides us with an approximate U(1)_(PQ) symmetry that forbids the generation of µ at the GUT scale, it also forces the SUSY-breaking spurion field to carry a nontrivial Peccei-Quinn (PQ) charge. This connects the breaking of supersymmetry (SUSY) to the generation of µ so that the same scale enters both. Moreover, the messenger sector naturally realizes the D3-instanton triggered SUSY-breaking model of [J. Heckman, J. Marsano, N. Saulina, S. Schafer-Nameki, and C. Vafa, arXiv:0808.1286.] so this scale is exponentially suppressed relative to M_(GUT). The effective action at low scales is in fact precisely of the form of the “sweet spot supersymmetry” scenario studied by Ibe and Kitano in [M. Ibe and R. Kitano, J. High Energy Phys. 08 (2007) 016.]
Gene transcription profiling in pollutant exposed mussels (Mytilus spp.) using a new low-density oligonucleotide microarray
No full textIn this study we describe the design and implementation of a novel low-density oligonucleotide microarray (the "Mytox-chip"). It consists of 24 mussel genes involving both normalizing elements and stress response related genes, each represented on the array with one or two different 50 mer oligonucleotide-probe reporters spotted in replicated samples on glass-activated slides. Target genes were selected on the basis of their potential involvement in mechanisms of pollutant and xenobiotic response. They are implicated in both basic and stress related cellular processes such as shock response, biotransformation and excretion, cell-cycle regulation, immune defense, drug metabolism, etc. The microarray was tested on mussels exposed to sublethal concentrations of mercury or a crude North Sea oil mixture. RNA samples were extracted from digestive glands of control and treated mussels for the synthesis of fluorescence labeled cDNAs to be used in dual color hybridizations. Transcription rates of two metallothionein iso-genes (mt10 and mt20), a p53-like gene and actin were quantitatively estimated also by real-time PCR to confirm microarray data. Significant alterations in the gene transcription patterns were seen in response to both treatments
"One-step isolation and biochemical characterization of a highlyactive plant PSII monomeric core"
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