9,196 research outputs found
Higgs alignment from extended supersymmetry
We consider the effective type-II Two-Higgs doublet model originating from
Dirac gaugino models with extended supersymmetry in the gauge sector, which is
automatically aligned in the simplest realisations. We show that raising the
scale at which the extended supersymmetry is manifest and including quantum
corrections actually improves the alignment. Using an effective field theory
approach including new threshold corrections and two-loop RGEs, plus two-loop
corrections to the Higgs mass in the low-energy theory, we study the
implications from the Higgs mass and other experimental constraints on the
scale of superpartners. We contrast the results of the minimal Dirac gaugino
model, where alignment is automatic, with the hMSSM and the MRSSM, where it is
not, also providing an hMSSM-inspired analysis for the new models.Comment: 37 pages, 13 figures. References added. Published versio
Architecture independent environment for developing engineering software on MIMD computers
Engineers are constantly faced with solving problems of increasing complexity and detail. Multiple Instruction stream Multiple Data stream (MIMD) computers have been developed to overcome the performance limitations of serial computers. The hardware architectures of MIMD computers vary considerably and are much more sophisticated than serial computers. Developing large scale software for a variety of MIMD computers is difficult and expensive. There is a need to provide tools that facilitate programming these machines. First, the issues that must be considered to develop those tools are examined. The two main areas of concern were architecture independence and data management. Architecture independent software facilitates software portability and improves the longevity and utility of the software product. It provides some form of insurance for the investment of time and effort that goes into developing the software. The management of data is a crucial aspect of solving large engineering problems. It must be considered in light of the new hardware organizations that are available. Second, the functional design and implementation of a software environment that facilitates developing architecture independent software for large engineering applications are described. The topics of discussion include: a description of the model that supports the development of architecture independent software; identifying and exploiting concurrency within the application program; data coherence; engineering data base and memory management
Frequency Conversion in a High Q-factor Sapphire Whispering Gallery Mode Resonator due to Paramagnetic Nonlinearity
Nonlinear frequency conversion is a well known and widely exploited family of
effects in optics, often arising from a Kerr nonlinearity in a crystal medium.
Here, we report high stability frequency conversion in the microwave regime due
to a nonlinearity in sapphire introduced by a dilute concentration
of paramagnetic spins. First, we produce a high stability comb from two
microwave fields at 12.029 and 12.037 GHz corresponding to two high -factor
Whispering Gallery (WG) modes within the Electron Spin Resonance (ESR)
bandwidth of the Fe ion. The resulting comb is generated by a cascaded
four-wave mixing effect with a 7.7 MHz repetition rate. Then, by suppressing
four-wave mixing by increasing the threshold power, third harmonic generation
is achieved in a variety of WG modes coupled to various species of paramagnetic
ion within the sapphire
Larger testes are associated with a higher level of polyandry, but a smaller ejaculate volume, across bushcricket species (Tettigoniidae)
While early models of ejaculate allocation predicted that both relative testes and ejaculate size should increase with sperm competition intensity across species, recent models predict that ejaculate size may actually decrease as testes size and sperm competition intensity increase, owing to the confounding effect of potential male mating rate. A recent study demonstrated that ejaculate volume decreased in relation to increased polyandry across bushcricket species, but testes mass was not measured. Here, we recorded testis mass for 21 bushcricket species, while ejaculate ( ampulla) mass, nuptial gift mass, sperm number and polyandry data were largely obtained from the literature. Using phylogenetic-comparative analyses, we found that testis mass increased with the degree of polyandry, but decreased with increasing ejaculate mass. We found no significant relationship between testis mass and either sperm number or nuptial gift mass. While these results are consistent with recent models of ejaculate allocation, they could alternatively be driven by substances in the ejaculate that affect the degree of polyandry and/or by a trade-off between resources spent on testes mass versus non-sperm components of the ejaculate
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