19 research outputs found
Rashbons: Properties and their significance
In presence of a synthetic non-Abelian gauge field that induces a Rashba like
spin-orbit interaction, a collection of weakly interacting fermions undergoes a
crossover from a BCS ground state to a BEC ground state when the strength of
the gauge field is increased [Phys. Rev. B {\bf 84}, 014512 (2011)]. The BEC
that is obtained at large gauge coupling strengths is a condensate of tightly
bound bosonic fermion-pairs whose properties are solely determined by the
Rashba gauge field -- hence called rashbons. In this paper, we conduct a
systematic study of the properties of rashbons and their dispersion. This study
reveals a new qualitative aspect of the problem of interacting fermions in
non-Abelian gauge fields, i.e., that the rashbon state induced by the gauge
field for small centre of mass momenta of the fermions ceases to exist when
this momentum exceeds a critical value which is of the order of the gauge
coupling strength. The study allows us to estimate the transition temperature
of the rashbon BEC, and suggests a route to enhance the exponentially small
transition temperature of the system with a fixed weak attraction to the order
of the Fermi temperature by tuning the strength of the non-Abelian gauge field.
The nature of the rashbon dispersion, and in particular the absence of the
rashbon states at large momenta, suggests a regime of parameter space where the
normal state of the system will be a dynamical mixture of uncondensed rashbons
and unpaired helical fermions. Such a state should show many novel features
including pseudogap physics.Comment: 8 pages, 6 figure
Heterologous Expression of ATG8c from Soybean Confers Tolerance to Nitrogen Deficiency and Increases Yield in Arabidopsis
Nitrogen is an essential element for plant growth and yield. Improving Nitrogen Use Efficiency (NUE) of crops could potentially reduce the application of chemical fertilizer and alleviate environmental damage. To identify new NUE genes is therefore an important task in molecular breeding. Macroautophagy (autophagy) is an intracellular process in which damaged or obsolete cytoplasmic components are encapsulated in double membraned vesicles termed autophagosomes, then delivered to the vacuole for degradation and nutrient recycling. One of the core components of autophagosome formation, ATG8, has been shown to directly mediate autophagosome expansion, and the transcript of which is highly inducible upon starvation. Therefore, we postulated that certain homologs of Saccharomyces cerevisiae ATG8 (ScATG8) from crop species could have potential for NUE crop breeding. A soybean (Glycine max, cv. Zhonghuang-13) ATG8, GmATG8c, was selected from the 11 family members based on transcript analysis upon nitrogen deprivation. GmATG8c could partially complement the yeast atg8 mutant. Constitutive expression of GmATG8c in soybean callus cells not only enhanced nitrogen starvation tolerance of the cells but accelerated the growth of the calli. Transgenic Arabidopsis over-expressing GmATG8c performed better under extended nitrogen and carbon starvation conditions. Meanwhile, under optimum growth conditions, the transgenic plants grew faster, bolted earlier, produced larger primary and axillary inflorescences, eventually produced more seeds than the wild-type. In average, the yield was improved by 12.9%. We conclude that GmATG8c may serve as an excellent candidate for breeding crops with enhanced NUE and better yield