23 research outputs found
F-theory, GUTs, and the Weak Scale
In this paper we study a deformation of gauge mediated supersymmetry breaking
in a class of local F-theory GUT models where the scale of supersymmetry
breaking determines the value of the mu term. Geometrically correlating these
two scales constrains the soft SUSY breaking parameters of the MSSM. In this
scenario, the hidden SUSY breaking sector involves an anomalous U(1)
Peccei-Quinn symmetry which forbids bare mu and B mu terms. This sector
typically breaks supersymmetry at the desired range of energy scales through a
simple stringy hybrid of a Fayet and Polonyi model. A variant of the
Giudice-Masiero mechanism generates the value mu ~ 10^2 - 10^3 GeV when the
hidden sector scale of supersymmetry breaking is F^(1/2) ~ 10^(8.5) GeV.
Further, the B mu problem is solved due to the mild hierarchy between the GUT
scale and Planck scale. These models relate SUSY breaking with the QCD axion,
and solve the strong CP problem through an axion with decay constant f_a ~
M_(GUT) * mu / L, where L ~ 10^5 GeV is the characteristic scale of gaugino
mass unification in gauge mediated models, and the ratio \mu / L ~
M_(GUT)/M_(pl) ~ 10^(-3). We find f_a ~ 10^12 GeV, which is near the high end
of the phenomenologically viable window. Here, the axino is the goldstino mode
which is eaten by the gravitino. The gravitino is the LSP with a mass of about
10^1 - 10^2 MeV, and a bino-like neutralino is (typically) the NLSP with mass
of about 10^2 - 10^3 GeV. Compatibility with electroweak symmetry breaking also
determines the value of tan(beta) ~ 30 +/- 7.Comment: v3: 94 pages, 9 figures, clarification of Fayet-Polonyi model and
instanton corrections to axion potentia
Freshwater mussels from South America: state of the art of Unionida, specially Rhipidodontini
Using Dynastic Exploring Recombination to Promote Diversity in Genetic Search
A family of recombination operators is studied in this work. These operators are based on keeping and using certain information about the past evolution of the algorithm to guide the recombination process. Within this framework, several recombination operators are specifically designed to preserve diversity within the population, while avoiding implicit mutations. The empirical evaluation of these operators on instances of two test problems (k-EMP and permutation flowshop) shows an improvement of the results with respect to other classical operators. This improvement seems to related to the increasing degree of epistasis of the problem
ThreeâDimensional Visualization of Blood and Lymphatic Vasculature in Tissue Whole Mounts Using Confocal Microscopy
P109 Can A Theory-informed Interactive Animation Increase Intentions To Engage In Physical Activity In Young People With Asthma?
Background Participation in regular physical activity improves aerobic fitness and well-being. For people with asthma the benefits also include reduced hospital admissions, absenteeism, medication use, and improved ability to cope with the disease. However, although people with asthma can exercise safely, children and young people with asthma are less likely to be physically active than their peers. Integrating the principles of user-centred design and the MRC Framework for Complex interventions a theoretically-informed interactive animation was developed to encourage young people aged 12â18 years with asthma to engage in physical activity. Methods A mixed-methods two stage approach was used. In stage 1 a user group (young people with asthma, parents, health professionals) used online consultation and discussion methods to inform the development of the intervention in a highly iterative manner (modelling). The theoretical basis for the intervention was then refined and converted into a 3D animation with accompanying action plan and volitional help sheet. In stage 2 a web-based Interactive Modelling Experiment evaluated effectiveness in three key areas: knowledge about asthma, inhaler use, and intention to increase physical activity. One-to-one interviews and focus groups were used to evaluate the acceptability of the animation and whether the theoretical basis was effective. Results Twenty three people were recruited to the user group. Facilitated by multiple online consultation methods the group was highly engaged throughout. Fifty-three individuals were randomised online to receive the intervention or control; 26 completed follow-up questionnaires (49%). The pilot online experiment supported the evidence base for the intervention but demonstrated that recruitment methods and loss to follow-up need addressed before a future trial. Though not powered to detect an effect on intentions and behaviour, the study revealed an impact on intentions to be active (increase) and on safe inhaler use (decrease). Qualitative feedback was positive across all groups, the intervention being well received and regarded as understandable, meaningful, engaging and potentially very useful within an asthma review. Conclusion We have developed a high quality, two part intervention regarded as meaningful, acceptable and potentially useful. Future work is needed to establish whether acceptability levels and perceived effectiveness translate into behaviour chang